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FAQs about Metal Halide & Halogen Lights and Lighting for Marine Systems 6

Related FAQs: Metal Halides 1, Metal Halides 2, Metal Halides 3, Metal Halides 4, Metal Halides 5, Metal Halides 7, Metal Halides for Small Systems, Metal Halides for 40-200 gal. Systems, MH for 200 gal. Plus Systems, Metal Halide Lamp Issues, Metal Halide Fixture Issues, Metal Halide Heat Issues, MH Repair Issues, Compact Fluorescents, Regular Fluorescents, Lighting Marine Invertebrates, LR LightingTridacnid LightingSmall System Lighting,

Related Articles: Metal Halide Light, & Lighting Articles, Coral System Lighting,

Finding A Suitable MH Reflector - 04/11/06 It has been quite some time since I had to go to the all knowing WWM Crew with a question, but since this is a continual learning hobby, I have returned! <<Indeed it is...for me as well...welcome back>> I am rebuilding my 65g reef tank due to a forced relocation.  I have 4x 96w VHOs and 2x 250w MHs.  It isn't hard to fit all the lights in the canopy (19"x37"), but I had to seriously mangle the reflectors to put them in the first time. <<I'll bet>> Basically the MH's parabolic reflector had to be partially bent closed from their ~13" width to about 8" and I had to cut the VHOs' reflector in half to about 5" each because I have 2x VHOs on either side of the centered MHs. <<Not so much an issue with the VHOs, but this would seriously affect your "spread" on the metal halides>> I want to put a "less mangled" reflector in the hood this time. What do you think about a simple 36"x18"x2" reflector instead of the mix-match I have now? Do you know where I can get such a reflector? <<Indeed I do!  PFO has a 36" parallel reflector with dual mogul sockets and "shelf" to mount your VHOs.  I have two of these over my 8ft tank.  Check out an example here:   http://oceanencounter.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=OE&Product_Code=P3PRW2MS&Category_Code=RSC  ...if you have any questions about the reflector, call Vince at Ocean Encounter...a very helpful individual>> Thanks (again) for the help! -Jeff <<Always a pleasure, EricR>> Metal Halide Lighting    4/10/06 Good Morning, <And good morning to you, Steve.> First I would like to thank you all for taking the time to share your experience. You all have been extremely helpful in the past. <You're welcome.>I have a question regarding metal halide lighting. I currently have a 29 gal tank that I am in the process of setting up. (mini reef) (I will be moving the inhabitants of a 20 long into it.) I am looking into upgrading my lighting to a 175 metal halide. I have searched on-line auctions and have found some really good deals. Most of the cheaper systems include a magnetic ballast. I have found other systems with electronic ballast for more money. Will the magnetic ballast be louder than the electronic ballast? <Yes.> Are there any other benefits to consider? <Electronic ballast provide more energy savings, slightly brighter light, longer lamp life, and reduced noise.> I don't have a problem spending a little extra to buy a better product. I just would like to know what the difference is before I make the purchase. Also will the 175 watt be sufficient? <Yes, would allow you to keep any coral/clam you wish.> I could upgrade to 250 or 400, but think this would be overkill for such a small tank. <Yes, much more heat also.> (I do plan on adding some actinic lighting and fans to ventilate my canopy also.)<A must.> Thanks for taking the time to guide me.  <You're welcome.  Do read here also, Steve. http://www.wetwebmedia.com/marine/setup/lighting/fixtures.htm James (Salty Dog)> Steve Lighting/HQI  - 03/28/06 James, thanks for your timely reply and sound advice. <You're welcome.>  After visiting a couple of LFSs to demonstrate the difference between fluorescent and HQI lighting, I think she's convinced that's the way to go. However, most of the 48" HQI fixtures I see for sale feature 2 150W bulbs. Is HQI that much better that 300 total watts will be sufficient, or do I need to look around for a higher powered unit? Do you think it would be beneficial to look into one of the combo HQI/PC fixtures I have seen on the market? Finally, there appear to be 3 basic choices for HQI spectrum bulbs, 10, 14 and 20K, what would you recommend? <Watt for watt, the High Quartz Iodide bulbs are much more intense than fluorescents tubes.  What you have to decide here is what you plan on keeping.  Being the 90 gallon is a deep tank, stronger lighting will be needed if you wish to keep SPS corals and clams.  If that is desired, I would go with a twin 250 or a triple 150 watt system.  The twin 150 HQI's will allow you to keep soft corals and most LPS corals.  Additional fluorescent tubes are not required.  I like the 14K lamps.  Do read this article and related FAQ's for more info. http://www.wetwebmedia.com/marlgtganthony.htm Thanks again for helping us find our way. <You're welcome.  James (Salty Dog)> Pearson Hurst.  

MH lighting fire...!!! - 03/25/2006 Hello WWM Crew, <Hi Rori - Tim answering your question today!> Tonight disaster struck!!! I love my fish tank and have been a reef tank hobbyist now for about 5 years, but tonight my fish tank SCARED THE CRAP OUT OF ME!!!! I do not know what to do??? My wife and I were sitting watching T.V. when all of a sudden we both smelt a plastic burning smell that got pretty strong. We started looking around the house because it smelled like something plastic was on fire!!! Then I walked into the fish room and the room was filled with smoke!!! It turned out one of my ballast to my Coral Life HQI's was smoking pretty badly. Now I'm not talking about a little smoke I'm talking there was a fire going on inside the case of the thing and smoke was pouring out of it, and it filled the room with black smoke. Now I am so scared thinking about what would of happened if I wouldn't have been home, my house could of burned down! Another thing I don't understand is I am very cautious when it comes to building something. I have these ballast bolted to my stand with a dedicated fan blowing right on them. Also I have a circuit protector that will shut everything off if anything goes wrong. Looks like none of this stuff helped out, I honestly think that if I was not home it would of started a fire, and it would of eventually turned into a electrical fire. I am debating now if this is worth the risk. I am so disappointed that I spent so much money on these Coral Life 150 Watt HQI's and they fail like this. I will be contacting them about this situation I have run into. In the mean time I have all the lights turned off in the tank due to I am scared the other two ballast are going to catch fire like this one did. So now my corals are in the dark for now??? Any advice what would you do in this situation??? Anxiously awaiting your helpful response on what I can do??? Thank You!!! P.S. I took the ballast apart and in the case where the actual round ballast is inside is all swollen looking and melted inside!!! <That is very concerning indeed! Do contact the company and include in your correspondence very detailed information on your current set up so that they may identify any problems with your arrangement. Also do a search through online forums - to my knowledge, this is not a common occurrence but there is of course the possibility of a bad batch of ballasts - in which case you may be saving many other aquarists from potential disaster! Try to find out exactly what caused this - and please do keep us informed so that we may warn others of this situation! In the meantime, you will need to take care of your livestock. Make sure that you do a number of considerable water changes - I am concerned that some of the smoke may have become dissolved in the aquarium water and can potentially cause significant harm. Your corals will need light or they will not survive for long - I would suggest, if you are presently unable to comfortably provide them with adequate lighting (your situation being completely understandable) then I would suggest contacting a fellow reef keeper or your LFS to see if either will hold your corals until you can rectify your lighting situation. The same applies to your fish, although clearly these are less dependant on light for their survival. Keep a close eye on your fish as the stress of this incident may cause disease outbreak. As I said, please keep us informed as to your findings! Thank you and wishing you the very best of luck!>

Metal halide lights   3/25/06 Hello,  If this is Anthony, I enjoyed the sushi dinner <James here and yucky pooh to sushi.> (this is Vincent the young boy you met at the Pittsburgh  aquarium society). I had a lot of fun, thanks for all the advice.  Here's  my question, do I need a UV shield over the fixture (it's not double  ended) . I just bought a new retrofit kit metal halide  250w 4300k <The color temperature <4300K> is not of much use if keeping coral is in mind.> light my dad and I will throw together a miniature  canopy thing. Its going to be 20in long and 15in tall since I'm going to  hang it over my tank.  It's going to be hanging over my 55 long. Will this work?  <I'd be sure to incorporate a glass top on the tank for safety sake, and consider ventilation. You do not mention use of a cooling fan.  It will get rather warm in the canopy and water temperatures will rise.>   Thanks for all the help.  <You're welcome.  James (Salty Dog)> Lots Of Light- Lots of Options!   3/23/06 Wet Web Media Crew, <Scott F. with you today!> I have a 300 gallon reef aquarium.  Because of price issues, I have ended up with 8- 175watt 20k HQI metal halides and 8-96 watt actinics for my lighting. The tank dimensions are 96L X 24 T X 36 W.  What issues, questions or arguments would you have with this setup versus say 4- 400 watt 10K metal halides? <To be honest with you, it sounds quite nice. However, the electrical draw may be comparable to what the draw would be if you went with the 4- 400 watt setup. My thinking is that the real issue might be the PAR value of the 20K bulbs versus 10k bulbs. If you're intending to keep high-light-loving Acroporids and other corals of this type, you'll get better growth out of the 10ks. On the other hand, I like the aesthetics of 20ks, and you may get nicer colors out of the corals. Having 8 fixtures means 8 bulbs to change, and 8 ballasts to service- essentially 8 things that can fail; 8 more things to keep track of. On the other hand, having 8 different pendants means that you can "put the light where you want it".> Will this lighting be sufficient for SPS coral or clams? <Either will suffice; all depends on your goals- high growth rate versus aesthetics.> This light setup is not really typical for this size tank- it seems- so that is why I ask. Thanks SO much Jason <No problem, Jason. I'd do the math, in terms of energy consumption, and examine which makes more economic sense in regards to your goals. Best of luck to you! Regards, Scott F.> MH Wiring Question  - 03/12/2006 Thanks for taking the time to answer questions, I have a canopy in my garage that is setup with 2 250 watt bulbs. I was wondering if it is possible to use one transformer to operate 2 lesser watt bulbs... I am building a canopy for a 55 gallon tank. How can I do this?  <Joe, you cannot do this, no mixing bulbs of different wattages.  Could start a fire here.  Local electrical distributors offer MH ballasts at reasonable prices, do check them out.  James (Salty Dog)> Lighting/Inverts  - 03/12/2006 Hi, my name is Danny Richards <and mine is James, how are you?> and I had a question about metal halide lighting for my 150 gal aquarium. The tank is 60"L x 24"W x 25"T and I am trying  to decide if I should use 3 x 250 watt MHs or 2 x 400 watt MHs. And also if they should/need to be DEs or Mogul. Other than being single ended or double ended,  what is the difference between HQI and Mogul?? I am wanting to keep SPS and  Clams with very few fish. Also what Kelvin rating should I use? I like the way  14K and 20K look, but I have had people tell me those color temps. are not good  for SPS and Clams. Thank you for your time, and keep up the good work! <Danny, to the best of my knowledge all double ended lamps are of the HQI variety.  The mogul socket is for metal halide and these lamps cannot be swapped using the same ballast.  I think HQI is the best way to go.  A little more intensity watt for watt, more compact in size, and generally produce truer color temperatures.  Bulbs generally last a little longer also.  I think two 250 watt HQI's should be enough for your tank, and I'd probably go with something in the 12-14K in temperature. James (Salty Dog)>                                                                               Danny R.

Lighting/Metal Halide Upgrade  - 03/09/2006 I have a 300 gallon reef tank. I am using Three 250Watt Metal Halides and four 110 watt Super Actinic VHO's. My SPS are at the top of the tank about 4 inches below the water and have never done well and always turn brown. I have all types of corals and fish. My tank is 24" deep by 96" long by 32" wide. The lights are 14" from the bottom of the bulbs to the surface of the water. I am considering replacing the 250 Watt with 400 Watt Metal Halides in hopes to create a healthier environment for my corals as well as being able to keep SPS from turning brown. Would this be a beneficial improvement/gain for the corals or only a gain for my electric company. <In a 24" deep tank that large, a definite improvement.>  If so what would be the best way to convert over? Change all bulbs over at once or one by one? I was thinking doing it one by one placing a screen just above the water to block some of the new intensity while continuing the normal light cycle. Then start poking holes in the screen periodically to start letting more light in over a couple of weeks of time. What do you think? <I'd make the transfer one at a time, wait a week before doing another.  Don't think you need any filtering as we are only going up 150 watts per week.  Not a great increase for the size of the tank.> I also just purchased a LUX meter, not really sure why but I heard it was nice to have. <My father-in-law was a gadget man.  We called him Inspector Gadget.> Any tips on how to use it and get the most out of it? <Just read the manual or ask the manufacturer.> The probe is submersible so I can check light intensity all the way to the bottom of the tank. Thanks for your help! I want to make sure that I do this right so that none of these animals suffer because of my stupidity!  <You are on the right track, Curtis.  James (Salty Dog)> Curtis Lighting/Inverts/MH   03/9/06 Hello Crew, <Hi Andy>      I have a question about how long I should acclimate my corals with the metal Halides.  The tank is a 150gal XH 48x24x31 that has 5inch sand bed 150 pounds live rock. The corals are pulsing xenia, Ricordea mushroom, green finger leather, toadstool, blue mushrooms, brown mushrooms, green hairy mushrooms, 2 starburst polyp rocks, green open brain, green Goniopora.  Inverts are bubble tip anemone with maroon clown fish, 4 cleaner shrimp, coral banded shrimp, pistol shrimp (somewhere in tank), green brittle star, black and beige brittle star, and a brittle star that came with rock never comes out maybe at night, numerous snails, blue legged hermit crabs and sally lightfoot crab.  Fish are small blue regal tang, 2 yellow damsels (that lay eggs all the time),2 Fiji devil damsels (male and female), 2 domino damsels, purple firefish, Midas blenny, lantern basset, purple pseudo and three green and blue Chromis. I think that covers them all.  Never thought all of them would survive that's why I have so many fish, <The idea is for them to survive.  Congrats.> plus the urge of having every fish that I see at the LFS. Filter is a tidepool 2 sump with PondMaster 700gph for return, 3 MaxiJet powerheads 295gph each and Excalibur skimmer and 2 250watt heaters. Okay with that out of the way for about a year I was using 2 pc fixtures that hold 4 bulbs each so I had 4 65watt actinics and 4 65watt 10,000k daylight  with a total of 520 watts.  Now I'm changing to a fixture that holds 2 250watt 10,000k MH and 2 96watt actinics with 4 1  watt lunar LEDs that sits about 3 inches from water.  How long should I leave the MH on I don't want to burn my corals. <I'd start with four hours and increase one hour daily.>   Is that enough power for hard corals? <Yes>  One more question.  When you guys say 4-5watts per gallon rule do you take account for the water displacement from the sand and live rock. <No.  The tank area is the same.  The rule of thumb can be a little iffy as a 150 watt HQI is more intense than 150 watts of PC lighting.  The depth of the tank also adds into the equation.> For example I have a 150gal tank but I only have maybe 110-120gal of water in it.  that just something I've always wondered. your recommendations would be highly appreciated. thanks, <You're welcome.  James (Salty Dog)>   Andy M57 ballast capacitor - 03/07/2006 Anyone on the crew know where a guy can score one or two capacitors for an m57 175w ballast? I've searched high and low.  <Dan, I'm sure I can get these for you as I'm in the industrial controls business.  I do need info on the capacitor such as voltage, microfarad capacity, etc.  I can check on availability and price at that time.> Help! Thanks, <You're welcome.  James (Salty Dog)> Daniel k. Babcock

Lighting/Inverts/T5 lighting for 180 Reef   2/22/06 Hi James, <Hello Roger.> After doing some additional research there seems to be varying opinions on T5 efficacy and I'd prefer to purchase a solution once given the expense.  Needless to say I also want what's best for the animals that will inhabit the tank.  Therefore I've decided to not step out of the box and go with tried and true MH.  I have a few related questions if you don't mind.  Any unsolicited advice is very welcome as well! 1.  I've read the rule of thumb is 1 fixture for every two linear feet of tank.  You'd mentioned two 250's but would 3 be more suitable? <Three would be more suitable if cost isn't a problem but if you went with two 250 watt HQI's placed on center 18" from each end (assuming a 72" long tank), you should have plenty of light.  Less light loving inverts can be placed on the ends.  Will only see some light loss on the last 6" of the tank.> 2.  10K bulbs seem to be the recommended frequency but there's different types.  One retailer alone sells Iwasaki, Ushio, Venture, Hamilton & BVL which vary by almost $40 in price.  Is there really a major difference between a $60 Iwasaki and a $95 BVL? <The more expensive bulbs usually produce a truer color temperature and a little more light output.> I'll be using an electronic ballast, probably an Icecap.  Not sure if that matters. <More efficient, bulbs last a little longer.> 3.  Strictly based on the bulb description the BVL sounds like it has more blue.  Does that negate the need for Actinics or are they still recommended?  Would a lower frequency blue be better either as an alternative or to augment the actinic? <In a mixed reef I would go with 10-14K lamps. Actinics aren't necessary with these color temperatures.> 4.  I'm going to be installing these in an 8" wood canopy.  What's the recommended ventilation scheme, number of fans, placement, vent holes etc? <Two fans, opted for the highest CFM you can get that will fit in the sides of your hood.   I'd place one drawing air and one exhausting air.> I'd really like to avoid buying a chiller but I don't want the canopy to sound like the inside of a data center either if I can avoid it. <Might consider Ice Caps temperature controlled on demand fans.> Also, should I add an insulating material between the pendant and the wood (it would seem wise) and if so what do you recommend? <I wouldn't, may melt/soften.> I apologize for dominating your time with all these questions but I'd like to preserve capital so I can afford to put something in the tank not just over it :) <I do recommend HQI, cleaner color temperature, bulbs last longer and takes up much less space in the hood.> Thanks so much, <You're welcome.  James (Salty Dog)> Roger Metal Halide Lighting   2/13/06 Hi All <Hello Brian.> I have an industrial metal halide 250W light encased in a box that can be suspended.. Will it be safe to use this above a 55 gall marine tank given that the light is only shielded by an ordinary glass plate? <Yes, but make certain that the unit is properly grounded, preferably to a GFIC receptacle.  James (Salty Dog)> Best Regards Brian

MH lighting...  - 2/15/2006 Hello James, Thanks for your feedback. <You're welcome.> I have a follow up question regarding the lighting.  The 250w HQI idea sounds good but I've read on wetwebmedia that some corals will not thrive under the intensity of 250w halides. <Yes, but not the corals you have in mind. The orange cup coral is one such coral that requires low lighting.> Do you see this as being a problem based on the corals I mentioned in my previous e-mail? <The 250 watt light was a suggestion if you were interested in keeping clams, Acroporas, etc.  I've witnessed soft corals along with SPS/LPS doing extremely well under 400 watt halide systems.   James (Salty Dog)> Best regards, Kevin Lighting question ... If James had to "put things away" or look for... would he make better, more accurate/complete titles? I think so : SW invert. lighting, MH  2/13/06 When I setup my 150 acrylic (65x22x22) I had a FOWLR in mind.  My lighting consists of 4x65 pc (2@10k and 2 actinics) which suited me fine and my fish fine.  However, I have discovered the way cool world of inverts.  I now have a couple colonies of mushrooms and a colony of yellow polyps.  I would like to add more polyps, softies, and LPS, but I'm not sure I have enough light to meet the "moderate light" requirements of those animals.  I have a closed loop return on the top of the tank which prohibits me from adding any more fluorescents, so I was wondering if I should go with 2x150 or 2x175 MH?  I'm not really sure what "moderate light" means, but I do know that the same wattage of pc vs. MH is night and day.  My tank has three cut outs of equal size across the top, so I was thinking one pendant over each outside opening (which is where the bulk of my LR is) and leave the middle third to receive indirect light.  Ideally, I don't want to change anything, but I also want to ensure that my animals (present and future) have what they need to thrive.  Your advice is greatly anticipated almost as much as it's valued. <Mike, your lighting level isn't really enough for the size tank you have unless you keep the colonies at the upper 1/3 level of the tank.  With the depth of your tank and the ability to place corals wherever in the tank, you should go with HQI's or halides.  Two 175 halides will let you keep soft corals and some LPS.  Do read here on lighting requirements for corals. http://www.wetwebmedia.com/corllgtg.htm  James (Salty Dog)>

Lighting/Invert/MH   2/14/06 Ames, Thanks for the quick response. <You're welcome.> I figured what I currently have was a little on the wimpy side.  Will two 175 MH handle my situation, or would three be better without being overkill? Or, would two or three 250 HQI lamps be an upgrade from the 175's or just a waste? Once the initial MH investment is made the prices from two to three or 175 to 250 is not that big of a difference. I don't plan on supplementing with actinics, so would you suggest something over 10K?  What would be the "best" configuration while still being reasonably responsible with my pennies? Again, you guys do a great job!!! <If you go with the three 175's you should be able to keep most light loving inverts.  It would not be overkill by no means. If you would like to concentrate on SPS and clams then I would go with two 250's.  Personally, HQI is the way I'd go.  They offer a cleaner color spectrum, last longer and require less space. As for the K, I'd go with 12-14K lamps. James (Salty Dog)>

Question about Metal Halides  - 2/11/2006 Howdy crew, Quickie on metal halides.  I have some SE Halide bulbs that were used for a few months max., but they have been sitting unused since for almost 2 years now.  Would these bulbs be "outdated" so to speak since they have been sitting so long, <Would not worry here... the elements are not terribly reactive at low temperature in a sealed, evacuated tube. 2 years is not long in this case.> or is the only important piece of info. the amount of usage time? <Pretty much... within reason. Best regards, John> Thanks for your time.   Paul

Metal Halide Retrofit - 02/07/06 WWM Crew, <<Howdy>>    I have a 46g bow front with the plastic hood/canopy in place.  Currently I am running the Coralife 2X96 watt PC system with integrated cooling fans, I should also mention that I have  approximately 7" clearance from the top of the hood to the surface of the water.  I want to upgrade to MH lights most likely with a retrofit system, what are my options to make this happen? <<Mmm....remove the hood and replace with a 150w MH pendant...maybe something similar to this: http://www.hellolights.com/aqadhatamo.html ...Regards, EricR

150watt metal halide. too much light?/Sunglasses for Corals  - 01/24/06 Question for you guys. Thinking of upgrading my lighting system for a 16 gal. nano reef. running for 3 years now) As of the moment using a 64 watt pc set up. Freakish amount of zoanthids, they are growing like crazy, dropping new little colonies all over and spreading over everything. totally cool!) <Great!> I have a few areas on the live rock that has Porites doing nicely, growing and spreading out also. Also about a 4 inch wide area  of Monitpora covered by a slight overhang. The Montipora is starting to lighten up in colour in the area that is under the overhang <Move it?>(duh!). Adjusting the rock to allow more light creates a very unstable rock formation. <Can use underwater epoxy cement.> My now long winded question is. would a 150 watt MH set up (aqua-medic mini pendant) be over the top in the light or would bumping up my pc set up to 128 watts be a safer direction. i.e.: little less heat,<Yes> less intense for the other inhabitants.<I'd opt for the 128 idea giving you eight watts per gallon, more than enough to keep most anything.> Would rather not blind myself/family if pendant needs to be a lot higher from water surface to avoid the heat build up, and end up wasting light. Any blunt/ honest info would be a huge help.( eyes are buggy from reading and talking to suppliers about this. some are all for it others are nuar.geo the pc route..)<James (Salty Dog)> POG

150 watt metal halide. too much light    1/25/06 COOL!, thanks for the speedy reply, <Just lucky, you were in the line of fire.> I will try the epoxy idea for the rocks, the rock the Montipora is on is a flat thin piece, sort of the middle center piece of the display but.." if can if no can no can"... again thanks for the freaky fast reply.. and for the wicked site, amazing resource for info!. <You're welcome.  James (Salty Dog)> Aloha POG

General Lighting Questions 1/23/06 HQI Hello, First thanks for being there to answer all of our questions, you folks are really appreciated out in the trenches. <Glad to be of service!> When we say to mount MH lights 8-12" above the water, does that mean the bulb or the bottom of the fixture? These would be HQI pendants in particular. <Generally, most people understand this to mean the distance from the lamp.> Also would you be willing to take a crack at this question (22" depth of water)....a 150 watt HQI mounted with the bottom of the reflector at 8" from the water is roughly equivalent intensity wise to a 250 watt HQI mounted at what distance above the water? <Hmmm... too many variables, but not more than about two inches, assuming that the same reflector is being used.  Not only is the distance itself a factor, but the spread of the reflector will come into play.  A light meter would be really handy for this determination.  Best Regards.  AdamC.>

MH vs. PC  - 01/24/06 Hey WWM crew <Hello.> Quick summary.... 55gal high (36w X 20h X 18d).  A friend of mine has to lights he wants to sell, just curious which one would suite my needs better.  I have about 60lbs live rock and about 1.5" sand (still cycling). I do plan on having 1 anemone and 1 or 2 soft corals with about 4-6 fish. The light specs are as follows: 280w Metal Halide 1- 155w HQI 20k <Are you sure it isn't a 150 watt or 175 watt bulb? Furthermore I would use a 10,000K bulb rather than a 20,000K bulb.> 2- 65w Actinic and 192w Power Compact 1- 96w Dual Daylight 10k & 6700k 1- 96w Dual Actinic 460nm & 420nm <Since you plan to attempt an anemone (and I urge you to be patient in trying such a sensitive animal) I would go with the more intense MH for your set-up.> I've heard stories of to much heat and light from a Metal Halide on a tank my size.   <If you suspend it at least 8 inches above the water, and have a small fan or two you should be just fine. Also look into a auto-top off system.> Both are same price, which do you think I should go with? <Given just these two choices I would opt for the MH, Adam J.> Metal Halide Bulb Switch   1/22/06 Hello!, <Hello Lani> Hope all is well with the crew.  I have a quick question I haven't quite found the answer to.  I have a metal halide system with 2 250 bulbs and ballasts.  However, I decided not to do a SPS only tank, and was wondering if I could use 175 watt bulbs instead? <Absolutely not.  You may start a fire.  James (Salty Dog)>

Double ended HQI bulbs   1/22/06 Hi guys!!!  I have said it many times but great site!!!!  Quick question....  Do you know what the white ends that hold double end bulbs into the pendant are made out of?  Is it ceramic??? <Yes> I got some shavings from the white pieces in the tank from the old bulb and could not get it all that fell in the tank.  Hope it is not bad for the fish and coral. I guess it there is nothing I can do about it now just would help for to get my mind at ease.  I do not want to wake up and my fish and coral are dead...  OK maybe a little exaggerated. <No worries.  James (Salty Dog)> Thanks Re: HQI bulb    1/25/06 Thanks for the quick reply. I have one more question. I always seem to see a sump setup or a wet/dry filter with a light over it. Is this recommended?  Just in case, I am currently running a 65watt. 50/50 Coralife fixture about 8"-10" from my wet/dry setup. should I remove it or leave it. and what are the benefits of such a setup thanks a lot. <Any sump you see with a light usually has a compartment that can be used for a refugium.  In your case there is no  reason to keep a light over your sump.  James (Salty Dog)> Are 150w HQI metal halides enough for my tank  - 01/23/2006 Thanks for the reply, James. <You're welcome> One more question: I was told 150w dual ended HQI's give off just about as much light as 250w mogul bases. <Don't believe this is true.> If this was the case, would 1 150w double ended HQI be enough over my 60 cube, or would you upgrade to a 250w double ended HQI? <As below, with the depth of your tank I'd go with the 250HQI for the critters you want to keep.  James (Salty Dog)>   Eric HQI bulb   1/18/06 Hello, <Hello Orestes> I am starting a 60 gallon reef tank and have a retrofit kit for two 65 watt actinics and 1 150 watt HQI double ended bulb. The lights sit about 5 inches from the surface of the water and my question is how should I place the bulbs so that I do not have any problems with the heat of the HQI affecting the actinics. Oh, I also have two 3" fans from Coralife one blowing cool air in and the other sucking hot air out. <The heat from the HQI will have no effect on the PC's.  James (Salty Dog)> <<I have a differing opinion. Would situate the fluorescents at a distance that is comfortable to your touch... RMF>> Thank You. <You're welcome> Orestes 180Gal Tank Lighting Question   1/18/06 Hello, I am relatively new to the hobby about 1.5 years and I just got a new 180gal Glass Tank. <Great> My question is about lighting.  I have 3 (1 was told I needed one every 2 feet of tank and since the tank is 6' long).  Which worked out pretty good because they go between the braces of tank. Anyway, I have  Mini Pendant System - 250W 14000K+ HQI Phoenix and Mini Pendant System - 2-250W 14000K+ HQI Phoenix. I have noticed some of your post and it looks like you usually recommend against MH lights? <??? Copy/Paste the reference> Anyway, since I have already spent the $1,000 or so dollars on this setup, what height should these be off water?   I have them mounted under the canopy to they are not very far off water, maybe 6". <I don't see a problem with 6" as long as you have a glass/acrylic cover over the tank.> Also, how long should I have these on during the day?  Right now my tank has just been cycling and I just moved.  <Really don't want to run the lights during cycling.> Moved my fish from my other tank over last night but I will be putting corals in any day now.  Mostly LPS, Anenomes, Inverts etc. <I'd start with 10 hrs/day.  James (Salty Dog)> Thanks! <You're welcome> Dave

Lighting   1/18/06   Hello - compliments on the site,<Thank you> my foray into reefkeeping would not have been possible without it.  I have a 55 gallon tank, about 20" deep and I am running Coralife lunar Aqualights (192w).  I recently purchased an LTA which is being hosted by a pink skunk clown and seems to be doing just fine, but I am considering upgrading my lighting so that I will not have to worry about lighting requirements in the future.  I like the new Current USA SunPod fixtures (2x150MH) - would you recommend this unit?  it does not contain any actinics, is this a problem? <A very nice unit.  I own a Current fixture and I can attest to the quality workmanship they provide.  The two 150HQI's will be great.  James (Salty Dog)> Thanks, <Welcome> Chris Which Lighting Spectrum? - 01/17/06 Hi Guys, <<Some sharp gals here as well.>> Rob here from South Africa. <<Howdy Rob...EricR from South Carolina here tonight.>> I just have a quick question. <<ok>> I ordered a lighting system that includes, 3 MH 250w each and 8 T5's.  My question is...The supplier only has 6500K and 14000K bulbs to choose from.  Which would be the best if it is going to be for a tank containing clams, Ricordea, and some other light loving creatures. <<As far as the critters are concerned, the 6500K will provide all they need as well as giving you the most PAR.  But most folks don't care for all that "natural" look and want a bit more "blue" to their "hue."  A good compromise might be to get the MH bulbs in 6500K and the T5s in 14000K.>> Always appreciate your help. Rob <<Always welcome, EricR>>

Metal Halide Bulb Replacement Question   1/13/06 Hey guys. <What's up Jason?> I'm a frequent reader of your FAQs and such. <Cool.> I have a question for you. <Okay.> I have a 40gal marine reef aquarium. I'm using a SunPod HQI lamp for the tank. Right now it has a 150 watt lamp in it at the moment. I wanted to know if it was possible to exchange this lamp with a 250 watt one. <No the ballast with the product you bought is only rated for a 150 watt bulb, equipping it with a 250 watt bulb would at the least under-drive the bulb and at the worst cause a fire. Don't do it.> I'd like to optimize the most light I can. <Though there will be some shadowing along the edges, a 150 watt HQI (generally speaking) is superb lighting for a 40 gallon tank.> Thanks in advance. <Welcome my friend.> Jason <Adam Jackson.> MH v Fluorescents, power consumption   1/10/06 Hi WWM Crew, <Hello Steve> I was reading one of the FAQ's when I came across a minor mistake and thought I would correct it. The WWM crew was asked if 150 watts of MH consumed the same amount of power as 150 watts of fluorescents and the answer was yes a watt equals a watt which is true but watts = amps x volts and a 150 watt MH light will consume more power or energy whilst supplying the same amount of watts, i.e.. more amps. The extra power is dissipated as heat from the ballast. <This particular answer may be dated.  The efficiency (power factor) of a system depends on the ballast.  Electronically regulated ballasts will be more efficient than a tar ballast and so on. This will also relate to light intensity somewhat.  On a 48" tank, two 150 watt HQI's are going to be more effective than 400 watts of fluorescents and generate less heat into the tank.  So now we are looking at light intensity versus wattage being used.  More than just watt for watt has to be considered here.> I hope this helps, regards, Steve. <I hope this helps also. James (Salty Dog)>

Lighting MH  1/10/06 Hey All, <Hey Jenna> Do you think I should get a second MH 400w pendant for my 50 gallon reef so I can have one on each side of the aquarium?  I find that my SPS are not as colorful on the sides and along the bottom of the tank... Or, should I purchase a Current 2x 150HQI double ended fixture?    Reason is, I can get a good price on it, but is it not enough light for the SPS? <On a 50 gallon tank the Current System is the way I'd go.> Any thought would help.  I really want the corals to grow faster, and show more color.  When I buy them from Reef and Fin in Connecticut, they are gorgeous, after awhile, they seem to fade a bit in my tank.    I am aware that many factors could be involved, but my water is awesome, and I am doing everything I can to keep these animals under   optimal conditions...<You must also use supplements such as strontium, iodide, calcium, etc to accomplish this.  I say this since you didn't state the use of such.  James (Salty Dog)> Thanks so much. <You're welcome> Jenna

MH light height  1/8/06 Hello all,   <Hello.> I hope the holiday treated you all fine ! <No complaints here, thank you for asking.> Just a quickie, <Sure.> have a 55 Gal Mixed salt water tank that's around 20in Deep from water surface to sand bed,  I have 2x250w 14,000k Halides running 10hrs and 2xActinic running 12hrs.  The lights themselves are rated for a tank up to 36in deep and the manufacturer recommends a minimum distance of 8in from the waters surface, however the lights are causing a temperature fluctuation of around 4 deg (79 to 83 deg) over the 10hrs. <That's not cool.> Due to the main tank being located in our family room I am unwilling to have a noisy fan running for 8hrs a day at this time and a chiller isn't an option. <X2, 3' computer fans won't, can't, even be heard over the noise of the average aquarium pump.>   With the lights being really more powerful than the depth of tank I have require at this time.   Would increasing the distance to around 12-15in to lower the heat transfer from light to water, have adverse effects on my Clams & softies (leathers, mushrooms, Xenia). <This distance (height) should be fine for your tank.> Happy new Year to you all from Wiltshire in the UK. <And a happy new year from SoCal, Adam J.> Lighting? Hi, <Hello> I have a 65 gallon tank that is 48" and 15" in depth. <Interesting>   My question is that I am upgrading my lighting to dual 250 MH with 4X65 (actinic) PC's. <Mmm, I would use 150 watt MHs here...> Both lights are mounted at the same level and was wondering what height I should have them above the tank. <Posted on WWM... likely about a foot> I have two crocea clams (bottom) that are my only light intensive animals.  I also have frogspawn and a Monti cap. Thank you in advance for your recommendation. Jose <Keep reading my friend. Bob Fenner> Metal Halide Lighting with Acrylic Tank  12/20/2005 Hi Girl(s) and guys, <Hello Jem> I have spent more hours than I care to remember reading information on your site.  It really is something to be very proud of on your part and has taught me so many things, however I am still slightly confused regarding MH lighting. I have a new acrylic aquarium 120" l x 30" h x 24" w (305 cm l x 76 cm h x 61 cm w)<WOW!> and am planning on putting two Arcadia 3 series pendants one 160 cm and one 110 cm pendant over the tank for light.  I am planning on having 5 x 250w MH and 2 x 58w and 2 x 30w linear fluorescent actinic tubes. The set up is for a full coral reef tank with hard and soft corals and Tridacna clams. Could you let me know if you think this is enough or too much light for this aquarium and what height I need to keep the bulbs above the tank - is 8 - 12" about right, <Yes> as I have read so many differing heights for placement of MH lights in various places.  As it is an acrylic tank it has large covered areas of acrylic across the top of the tank and two large uncovered areas.  Presumably, and from what I have read, the MH bulbs should not affect the acrylic on the tank - is this so? <Yes, heat will affect the acrylic if the bulbs are too close without fan cooling.> if it does affect the acrylic what other options do I have? or do I have to try to place the MH bulbs in the areas where there is no acrylic covering? <I would have lids made for the two large openings.  The acrylic does act as an excellent UV filter.> Is it possible to put MH bulbs inside a canopy of an aquarium?  I assume they would be too close to the top of the acrylic tank and water surface? hence the use of pendants by most people. <It's done all the time but on a tank 10' long it would cost a pretty penny to have one made out of furniture grade wood and probably a gazillion cooling fans.> Also what is the best light range to have 6500K - 10000K or a mixture of 6500K - 10000K and 20000K? <I like the 10K to 20K range.> Can you have too much lighting for marine fish? <Yes, but you shouldn't>  i.e. is the amount of light I am planning going to affect the type of fish I can have in the aquarium and if so where can I get information on this matter. <Search our WWM for info on fish before you buy so you know their requirements.  Getting back to the lighting, with your 30" deep tank, the 250watt bulbs will be borderline, especially with the pendant where they will need to be about 10" above the acrylic.  If this were my dream I'd go with five 400 watt MH systems and place one light one foot from each end and the remaining three at two foot centers for an even balance.  I'd also eliminate the fluorescent tubes altogether. I'd also consider air conditioning this room also.  James (Salty Dog)> Thanks in advance for your help on my questions. <You're welcome and Happy Holidays to you.> Regards Jem

Re: Metal Halide Lighting with Acrylic Tank  12/26/05 Hi, <Hello Jem> Thank you for your helpful reply regarding my pervious questions. <You're welcome> Further to your reply to me suggesting using 400w metal halide lights I have looked for pendants with this power and have found that Aqua Medic makes the Aquaspacelight 400 metal halide pendant.  These units come in 120 cm length (2 x 400w MH) and 60 cm length (1 x 400w MH).  The question I have is that as my tank is 120" l x 30" h x 24" w (305 cm l x 76 cm h x 61 cm w) would it be better for me to have two of the 120 cm units leaving a gap between them or two 120 cm units and one 60 cm unit and have the units extending past the length of the tank? <Doesn't do much good extending past the tank itself, wasting energy.> I presume the two times 120 cm units are the way to go and if so what spacing should I leave between the units? <Not familiar with Aqua-Medic fixtures.  I'd contact Aqua-Medic regarding spacing since I have no idea how far the light spreads from these pendants.  Go here;  www.aqua-medic.com.> Will 4 x 400w MH bulbs be enough light for this size tank? <I'd feel comfortable with it.> If not, the same company makes 1000w pendants that are 60 cm.s long and I could use three or four of these units? <Overkill> Just to remind you this tank is for a full coral reef set up with hard and soft corals and Tridacna clams. <Understand> Thanks again for your comments and recommendations which are very informative and helpful to me. <You're welcome.  James (Salty Dog)> Regards Jem Metal Halide Suspension height  12/5/05 Hello all, <Hi Paul.> Thanks so much for all of the support, I have a question. <You are welcome and sure.> I have recently upgraded my lighting system, I had 220 watts pc w/ flo actinics. Well my tank is your normal run of the mill 90 gallon, 4 ft. long and 24' tall by 18" deep.  Well I have recently acquired a HQI retrofit kit: dual 250 watts with 14000k bulbs (real pretty with a hint of blue) <Yes I admit the 14000K and 20000K bulbs are aesthetically appealing but in all honesty your photosynthetic animals will prefer lights in the 6500K to 10000K range.> so I rebuilt a new canopy (a lot taller) than the original; this sets the HQI bulbs exactly 9 inches from the surface of the water (from the protective U.V. glass to the water surface) I have slowly introduced these new lights over a period of about three and a half weeks increasing light exposure daily. Everything looks o.k. so far. <Sounds good.> I turn on my pc 96 watt 50/50 first thing in the morning for about a n hour and then introduce the HQIs (then turn off the pc's) I run the HQIs for about 8 hours and then turn them off and run my pc's again for a 2 hour period (trying to simulate the course of a day). <Right.> I currently have: 150 lbs. live assorted rock pulsing xenias 1 leather toadstool 1 open brain coral 6 green Ricordea mushrooms flower pot (Goniopora <Goniopora, a notoriously short lived animal in captivity.> (sorry about spelling) <No worries.> button polyps 1, yellow tang, 2 percula, 1, 6 line wrasse, 2, green Chromis, 1 dragonet mandarin, <I hope you are aware of the needs of this animal, it's in direct competition with the six line wrasse for its food source'¦they aren't the best tank mates to say the least.> 1 brittle star, and clean up crew. Should I modify my canopy to bring the lighting even farther away? I know I should be 8-12 inches or so according to the board but my tank is shallow for a total of 500 watts of HQI. <You can get away with 9' in this case, as long as the temperature is under control and everything is well ventilated. This is a lot of light for the animals you have but it will also allow you to attempt more light demanding species in the future.> How high would you recommend I bring the lights from the surface of the water. <At least 8', which you have done.> Oh yeah...by the way the back of the canopy is fully open and I run one small pc fan in the back it seems to keep the wood canopy slightly warm to the touch and the water temp a constant 79 degrees. <Yes these lights are very hot, as I'm sure you know. There will always be some detectable heat with this set-up (I've burned myself on mine quite a few times'¦and been shocked by them, long story, anyway just be careful) as long your temperature is stable and there is no 'over' heating where it becomes dangerous (for you), this is fine.> thank you for any help in advance. <Welcome.> Paul <Adam J.> HQI lighting units  12/10/05 Hello Wet Web Guys & Gals; <Hi John.> <<A gal waves.>> I currently am planning my next reef aquarium.  <Ooh, fun.> I will be upgrading from my four foot 90 gallon tank (by nature of it's/my evolution, is a bit of a garden reef) to a six foot x 18 inch tank (I would prefer a 24" wide tank, but it would be too tight in our living room) which will be either 24 or 29 inches tall.  <24'd will be easier to clean and light.> As a consequence of this, I am looking into lighting systems. I have looked at the various tanks featured in Michael Paletta's "Ultimate Marine Aquariums", and it seems that the popular way of lighting a six foot tank is with three 250 watt metal halides. Sensible enough. But, I may prefer to use a pre-built fixture such as Coralife's Aqualight Pro (rather than cobble up something myself), which comes with 3 x 150 watt HQI's for some reason. <This is a pretty good fixture though there are a few other prefabricated units (which can also be ordered in the HQI format) made by other companies that I prefer, PFO and Hamilton to name a few.> Now, I have perused the FAQ's as well as some other material, which leads me to believe that the lower power HQI's may be as bright as the higher power single-ended lamps. <Possibly, if you compare a 150 watt HQI bulb and a 150 watt standard MH bulb (just the bulbs themselves) they are about even in terms of par production. However the small profile of the HQI bulbs allows them to be teamed up with much more efficient reflectors and thus an HQI bulb of lower wattage can match the output of a single ended bulb of higher wattage.> Or, maybe not. It's a shame that these things are rated by watts rather than lumens! <I agree.> Anyway, do any of you have experience with this? <Yes I use an HQI unit made by Hamilton and am very pleased with it.> Can 450 watts of HQI effectively light a reef tank, with the ability to keep some Acroporas? <The x3, 150 watt HQI would be fine for keeping most photosynthetic animals anywhere in your tank except possibly on the bottom you go with the 39\u201d height.> Maybe some clams? <Most clams will be fine with this lighting, squamosa and derasa in the sand, Croceas and maximas in the rockwork.> It would be nice to get the equivalent of 750 watts of traditional MH lighting but only use 450 watts of power!  <You can make this lighting work.> Yours in Reefing; <Good luck with the new set-up.> John <Adam J.>

Metal Halide Choices'¦I like HQI units  12/8/05 Hello, <Hi James, this is Adam J helping you out tonight.> First I really appreciate the service you provide. <And I enjoy providing it.> I have Mr. Calfo's Coral Propagation book on the way from Amazon as we speak. <One of my favorites.> Looked though the FAQ's and a couple came close, but no cigar. So.... <'¦here you are.> Decided to jump into the reef world. I have an odd shaped tank, a 92 corner, that I am having trouble lighting, like lots of other people. I have built a nice custom hood that has 10" of clearance to the top of the tank. Being new I am going to try LPS and maybe a frag or two of SPS and I sure do think clam's are cool. <Oh me too, Tridacnids are awesome.> I have narrowed this down to two options. I under stand MH lights cover about a 2x2 window and my choices come down to space constraints. <Okay.> Option 1 is a single 250w mogul 10k retrofit style lamp in the middle of the canopy with (3) 1x55w PC's situated around the MH lamp. <A good option, though I would rather have T-5 HO or VHO over the PC's though as you mention space constraints may not permit this.> Questions; <Of course.> Will this be bright enough on the edges of the 2x2 box the MH covers, there would be a good 16" on either side of this window of light. <Obviously there would be some areas that receive more light than others. Though I don't think you would end up with any 'drastic' shadowed areas.> Would this allow me to keep a clam on the sand bed and some light loving corals in the middle of the 2x2 window? <Depends on the Clam, Squamosa and Derasas on the sand bed would be fine, Croceas and Maximas should probably be closer to the light in the rock work.> Option 2 is two 150w HQI pendants along with a 1x96w PC in front and a 1x55w PC behind. <I like that option a lot better. This would allow you to keep mostly any photosynthetic animals anywhere in the tank.> Questions; Where the two 2x2 windows of light overlap would this in effect be close to a 250w light? <No it would be much more intense. 1, 150 watt HQI bulb has about the same par reading as the average 250 watt SE, mogul, bulb. The reflector and small profile of the HQI bulb allows for much more efficiency.> For example where there is overlap would I be able to keep a clam down on the sand bed? <See above.> Also could I keep any corals down on the sand bed where there is only single coverage of one of the 150w HQI's? <Yes the as long its not a brightly colored (ultra light demanding) SPS such as an Acropora most should be just fine, especially the LPS you mentioned.> Final question, which one do you recommend? <I immensely prefer your second option of the duel HQI units.> Thanks so much! <You are quite welcome.> James <Adam J.> 

Re: Lighting Upgrade  12/15/05 This lighting would not be too much for my other corals? <Some specimens may have to be placed on the bottom (The 'shrooms come to mind) and they will ALL have to acclimated tot he intense light, search WWM Re: light acclimation.> Thanks again, this really helps. <No Problem.> Jose <Adam J.> Re: Lighting (Boiling) Upgrade  12/15/05 Hi, <Hello.> Is a dual 400watt metal halide (PFO Brand w/10K bulbs) enough light to keep a crocea clam and Acro corals in a 70 gallon tank (15 inches deep)? <In my opinion, WAY to much light, x2, 150 watt would-be plenty for just about anything in this tank.> Thanks and I appreciate your assistance and website, <Quite Welcome.> Jose <Adam J.> Metal Halide Lighting, Fixture Manufacturer Contact Information, Kudos  11/30/05 Crew-  <Craig> I just wanted to pass along some contact info to our fellow reef keepers.  There is a manufacturer located in Indianapolis, Indiana who builds metal halide setups with remote ballasts at extremely competitive prices. I do not work for him, I just found him on eBay. I was a bit skeptical as to how quality his products were (especially at the prices being asked) but since I live in the area, I visited his facilities in person.  About six months ago, I bought both metal halide units that were 400W w/ a 20K bulb and 250W w/ a 10K bulb. The 400W ran me $110 and the 275W was $90. Both units came with a 2 year warranty. His prices are absurdly low, but the units are quality, and I would recommend them to others. He does charge for shipping (don't know the rates). He prefers PayPal for payments, I am not sure if other payment methods are offered. These units have done very well for me, and since this hobby tends to break your wallet, I just thought I would pass the info along. I am not one for hawking products for anyone (or for any reason, really), but he has been a solid guy in his dealings with me and others in the area. He has been in the business for five years, and I told him I would refer him to others since he has only recently expanded his business from horticulture to marine applications. His contact info: Michael Hurrle Indoor Sun (Indianapolis, Indiana) M3i6k0e@aol.com  317.345.1369 If you can, please post this info for others to use. Thanks! Craig  <<Done!  Marina>> <Thanks for sharing, Craig. I'm sure this will be posted on the daily FAQ's. James (Salty Dog)>

Lighting follow-up - 29/11/05 Could you please tell me the difference between a Aqualine Buschke, Super White Blueline, an Ushio, and a XM , all of which are 10000K MH? <Your choice will come down to aesthetic preference. Ushio, XM and Aqualine are all very good brands. I have found AB bulbs (never tried 400 watters, mind you) to be excellent in terms of quality, but a touch on the yellow side for my tastes. Despite this, corals do seem to love the light, and the yellow can be balanced with actinic supplementation. Many people rave about the colour of the XM bulbs.  I would urge you to look at reviews of these brands, pictures of people's tanks, and decide for yourself. In addition to reading through our lighting FAQs, it would also be worth checking out Sanjay Joshi's excellent site on lighting here: http://www.reeflightinginfo.arvixe.com/> I want to buy the best one for my reef. I also have a 96watt Coralife. Is it a good idea to use this along with the 10,000K MH for aesthetic? <Yes, an actinic would help balance out the slightly yellow caste to some 10,000K bulbs. However, whether the intensity would be enough to make any major dent on the output from a 400W halide is questionable. One thing is for certain: You have a great deal of light over a 50g tank.> Thanks. Ron/Jenn <Best regards, John> 

Metal Halide Lighting And Acrylic Tanks - 11/27/05 Hi, <<Hello>> I've searched and researched my question, but have come across no answer so I wanted to run it by you. <<Alrighty>> I have a 75 gallon pentagon acrylic tank. I am considering purchasing the Aqualight Pro with the 150 watt metal halide and 2X65 watt actinics. My tank has a closed top with a removable acrylic piece that covers it. <<Typical>> Using the mounting legs, would I have to worry about the heat melting the top of my tank? That may be a stupid question, but I'm new to metal halide lighting and can't find anything to answer this. <<Not a stupid question. Keep the bulb height 6"-8" above the tank and you'll be fine. I would also remove the "removable" piece to aid with light penetration/gas exchange.>> Thanks for your time. Brian <<Welcome, EricR>>

Metal Halides And Lens Covers - 11/27/05 Hey crew! <<Hey Jenn!>> Thanks for all of your great info! <<You're welcome>> Quick question: currently running 50 gal reef tank with 400w 20K bulb and it hangs about 8" from the water's surface (We love SPS). <<Yowza...a lot of light!>> There is no cover on the tank, but could we take the glass cover off of the halide fixture in order to let more light get to the tank? <<If this is a single-end bulb (Mogul) fixture, yes...if a double-end bulb (typically referred to as HQI) fixture, no...>> Would it be dangerous? <<It is generally accepted that the Mogul style bulbs provide enough UV protection with the outer glass envelope that is an integral part of the bulb. It is also generally accepted that HQI style bulbs need the glass (or plastic) lens of the fixture to provide the necessary UV protection. I run Mogul style bulbs and I "don't" use any type of lens/cover.>> We noticed that a few LFS's do that. We have found that when we bring SPS home, they lose some color compared to what they had in the store. <<Mmm...coral pigmentation/color is not always about light, though if it were me I would change that 20000K bulb out for one of 10000K. Other things to consider to help with coral color are water quality (use of carbon, ozone, skimming), water flow/movement, and coral feeding.>> Thank you! Jenn <<Welcome, EricR>><RMF is concerned with the possibility of splashing water, burned elbows...>

Re: Metal Halides And Lens Covers - 11/27/05 Thanks a lot!! <<You're welcome Jenn>> What do you mean by ozone? Is that UV Sterilizer?? <<Nope...though some models do use a UV tube to generate the ozone. Ozone can be/is of great use...have a read here and the indices in blue if you wish to learn more: http://www.wetwebmedia.com/ozonefaqs.htm >> I use a wavemaker with 3 Maxi Jet 1200's, and my Blueline 40 with a SCWD on the returns. My skimmer is the AquaC 150. It rocks... <Indeed...a good skimmer.>> Feeding is a question. I use Kent ChromaMax once a week, and occasionally Cyclop-eeze. <<Personally, I wouldn't use the Kent product...of dubious utility.>> I also have PhosBan Reactor. Should I just lose the Coralife 96 watt actinic all together? <<Not if you like it...but your corals don't need it.>> Or maybe switch it to a warmer spectrum, like 6500K??? <<Now you're talkin' <G>. You will also realize a higher PAR with better penetration.>> Thanks again. Jenn <<Regards, EricR>> 

Lighting A Shallow Reef Tank - 11/25/2005 Hi guys, I sure need help. <We all do now and then! Scott F. with you today!> I am setting up a 60gal. 48x15x16 long but not very tall. My dream is to make it a more SPS coral tank with a few leather corals that I have in a 15 gal.  Because the height of the tank is lower than most, I can't decide on the proper metal halide wattage. I was thinking 2-175 watts with 2 96 watt actinics. After 3 in. of sand and a short stack of live rock, maybe just 6-8in.high, would this be to bright and bleach the corals? <It could be too bright for some corals; in fact, and new coral needs to be acclimated to new lighting conditions. For greater versatility and energy savings, I'd consider going with two 150 double-ended (HQI) reflectors (like Sunlight Supply "Reef Optix III's or Aqualine Buschke or PFO pendants. They throw good light over a wide area. Most of the commonly encountered high light loving SPS corals should do okay under these lights in this sized tank.> And would it be to hard on a few fish that I want as well.  The lighting I looked at sits between 4 and 7in above the tank. <Depends on the types of fishes you intend to keep. Deep water fishes will require a dimmer setup or more rocks or overhangs to retreat to if the light bothers them. Also, consider heat issues in a shallow tank. Be sure to properly ventilate the canopy.> Thanks Bob Carter <My pleasure! Regards, Scott F.>

Another one of those Lighting Questions  11/16/05 Hi, I'll make this short, I have a 300 gallon, standard size 8' long x 30" high. I have gotten rid of all of the sharks and eels from it and am taking my existing reef tank and moving everything to the 300 and downsizing to one tank. From there I will the begin the long and expensive process of populating it. So, I already have 2 175 12,000k Sunburst bulbs on the 100 reef. I want to utilize the 175's so that I can save money, so what I am considering is 2 250 watt 14,000 halides on either end and the 12,000 175's on the inside, along with 4 65 watt Actinic PC's. <For looks, I'd put the brighter, higher watt MHs in the middle.... the lower on the outsides> Now, keep in mind that I live in the Los Angeles area and electricity is really expensive. <Am just south of you... and understand> If I can have SPSs at the top of the tank I would be happy and all other mushrooms and LPSs lower in the tank. What do you think?? Thanks <Can be done. Bob Fenner> 

Halogen vs. metal halide 11/6/05 Hi guys  <Hello Archie> I would like to know if plain halogen lamps will be as effective for corals and anemones as metal halides would be?  <I don't know of any halogen lamps that would be an effective replacement for halides. James (Salty Dog)> 

Metal Halide Bulb Brands 10/30/05 Hello Mr. Fenner, <Actually Adam J with you this morning.> I was wondering if you had any information about the Iwasaki 50k de metal halide bulbs available. <I have only seen this bulb in usage once and I do not have any personal experience with it though I have used other XM bulbs and they are a "Quality" brand as for the Kelvin rating...its aesthetically pleasing but most animals hosting zooxanthellae prefer bulbs with temps in the 6500K to 10000K range. You could use this bulb to supplement a lower temperature bulb to get the look you want.> I know they have been talked about before but I thought by now there would be some better evidence about whether they are any good or not, when used over a reef tank. <See above.> thanks Ben Hustwayte <You are welcome, Adam J.> 

Reef Lighting and Kelvin Ratings 10/27/05 Hello and thank you in advance for your needed help! <Hi Jon, and umm'¦your welcome in advance.> I am currently thinking of expanding my horizons of aquarium size and have a lighting dilemma. The tank that I am getting is 180 gallons which is 72x24x24. On my current tank I am running one 10k 250w AB HQI with VHO actinic. My livestock is a mixed garden (including SPS and clams) to say the very least.  <Ok, so a shallow water biotope.> My questions are the following: would one more equal halide fixture be sufficient on a tank that size; or would three be better?  <Three is the recommended number if you want to continue with the SPS and Clams. One bulb per 24' of tank length is a general recommendation.>  Also I am considering moving from 10k to 20k (also in the AB line of products) in order to achieve a bluish white color. Would my mixed garden corals suffer from this regiment of lighting; or should I remain on the path that I am currently following?  <Mmm, photosynthetic animals prefer lighting in the 6.5K to 10K spectrum so out of three of your bulbs I wouldn't go all 20K. 14K at the most, but honestly 10K with VHO actinic supplementation is the best way to go in my opinion. Maybe you could mix bulbs, a 20K on the middle with 10K on the ends. Its your choice in the end, and you probably could get away with 20K but some animals may have to be left out and expect slower growth.>  Do you have any further suggestions of how I can achieve the 'look' for my aquarium that I am seeking? <Just the above.> Thank you very much for your time and expertise. It is greatly appreciated! Respectfully, Jon <You are welcome, Adam J.> 

Metal Halide (UV) Shielding - 10/13/05 Hello all and thanks ahead of time, <<Howdy>> Am somewhat confused at why MH spotlight type pendants are able to be shielded in pendant and HQI fixtures are able to be shielded in pendant, but MH hoods and canopy lights cannot except for a lid on top of aquarium at some distance from bulb. <<Not sure where you got this info, but most any manufactured light fixture, whether pendant or otherwise, mogul or DE, will come with some type (plastic/glass) lens (shield) attached to the fixture. I wonder if you might be referring to the argument on "whether or not" to shield MH bulbs? There has been some debate on this, and many folks choose to shield HQI/DE bulbs because they lack the outer glass envelope of a mogul bulb. You can argue that the sun has no such shield, and there are writings stating that much of the colorful pigments seen in some corals are proteins produced to "shield" the corals from the sun's UV...but most folks will err on the side of caution and shield their HQI/DE MH bulbs. I currently utilize mogul bulbs, and I don't shield them.>> Are HQI / mogul type spot pendants and fixtures less hot than canopy / hood MH lights? <<Not as a rule...depends on design, wattage, presence of electric fans...>> Just finished Mr. Calfo's Book of Coral Propagation. Rarely is a book so informative and fun/entertaining at the same time!!! <<am much in agreement>> Bravo A.C. and thank you all, Peter Puzzled in Lakewood, Ca <<Regards, EricR>>

Re: Metal Halide (UV) Shielding - Follow-up 10/15/05 Thanks Eric!!! <<Most welcome>> To follow up then, the MH mogul type aluminum hoods with a fan on each end can be shielded right there on the hood, similar to a fluorescent fixture? <<Sure...will likely come with some type of splash guard which also functions as a UV shield. Some materials (treated) are better than others, but any glass or plastic lens/splash guard will filter "some" UV.>> If so then is it placed directly on tank top, suspended, mounted or any of the above? <<Is up to you...but I don't recommend placing (resting) the light fixture directly on the tank top. Allow a couple inches for air circulation...some fixtures come with little "feet" for this purpose.>> And for retro fixtures attached to wooden canopy top, can the bulb be shielded at the fixture instead of having to cover the tank with a sheet of glass/acrylic? <<This can be done by attaching to the hood, yes. But if you go with mogul bulbs I don't see the need myself.>> I've never seen moguls shielded in a retro fixture for some reason. I am a safety consultant by profession and it makes me cringe to see those exposed bare bulbs above the water. It gives me a "0" comfort level. <<Little to be concerned with here, really...the mogul bulbs are already shielded by the outer glass envelope. The biggest danger in my opinion is breakage caused by splash on the bulb, and even this is minimal. Most folks are trying to get all they can out of their lighting, and adding a "shield" only reduces intensity/PAR.>> Just like all the tanks I see set up relying on check valves to prevent back siphoning. Arggggh! Or single hole overflows!!! etc. <<agreed>> Please indulge my "safety first" nature with my above concerns regarding the MH's. <<No worries mate, you have to do what makes you comfortable. You can still provide adequate lighting for your wet pets with a little planning.>> THANK YOU and BE SAFE Peter Lakewood, Ca <<Always welcome, EricR>>

More On MH Lighting Shielding - 11/18/05 Thanks Eric!! Getting clearer. One more follow though, please. I have read on your site that by mounting MH too close to the tank top this has caused the glass to crack/acrylic to melt.  If true, what material is used to shield bulbs in fixtures (like HQIs for instance that does not crack/melt so close to bulb?? <<Tempered/treated glass...adequate air flow around same.>> And why does tank brace crack, but not shield glass? <<Not usually tempered/treated to withstand extreme heat.  Keep in mind too, the glass used to shield the bulbs is not under the same stresses the tank brace is (i.e. - bracing together a tank full of heavy water).  As for plastic, some of the bell-type pendants use plastic/acrylic shields.  These don't "melt" due to the air flow around the fixture, but, place it too close to the tank top and restrict that air flow...you get the picture.  Ideally, you won't have a cover on the tank (reef tanks especially, need to "breathe"), and most fixtures with multiple bulbs are designed to place them on either side of a center-braced tank.>> Sorry for follow ups, just want to be clear on this. Thank you Peter <<Follow-ups are no problem my friend, EricR>> Aquatinics MH Hoods - 10/15/05 Hi Eric, PS--please check this Aquactinics.com site for MH hoods that can be set right on top of tank and contribute almost zero heat. What do you think, please? Skeptical but intrigued in Lakewood Peter <<Mmm, might be fine but like you...am skeptical. I would still conspire to raise the fixture by an inch or two...perhaps fashion some "legs" from acrylic for this purpose. I'm guessing you noticed the UV splash shield? <G> EricR>>

Question About CRI Colour Temperature and UV Filtering  9/17/05 Hi Crew, <Hello Brad> I looked in the posts to try to find the answer to this question. I found the question was asked but I did not understand the answer posted. I am researching metal halide systems and found that bulbs in the 5000 to 5500K range have High 90+ CRI values. When looking at higher temperature bulbs (10000K) I notice that the CRI drops to around 65. These numbers are taken out of manufacturer catalogs for commercial bulbs. It makes sense to me that the CRI will drop the further you get away from the 5500K  mark. I just want to ask if my assumption is correct,<Yes> or if there are some special marine designed bulbs in the upper temperature range that have higher CRI values. <A color rendering index of 100 would be equivalent to high noon in the tropics, that is, the most natural color.  A lower CRI does not necessarily mean the light is no good for your corals as certain wavelengths filter out very quickly the deeper the light penetrates the water. These high temp bulbs at the proper wattage per gallon (4 to 8) provide enough intensity for the corals to live.  The higher temperature bulbs (10K+) are closer to the color you would actually see on the reef.  Hope this makes sense.  Just got back from the madhouse in Detroit and the mind is foggy.> I also read in one of your articles that unshielded bulbs can put out dangerous UV A, B,& C rays and must be filtered. Is a piece of glass placed on the output end of the fixture adequate to filter these harmful rays, or are there special lenses you need to get for filtering purposes. If you need special lenses do you know of any sources?  <Glass works, but acrylic is better, no special lenses needed.> Thank you for your help. <You're welcome, James (Salty Dog)> Brad

MH lighting help  9/2/05 Hello WWM,<Hello Cody> I have read several Q&As on your site using the search tool and threads on other sites and can't find a straight forward answer to my question.   My apologies if this has already been asked and I cannot find it. I am thinking of upgrading my lighting over my 75 gal (48x18x20H) from 4- T5 / 2-VHOs to metal halide. This combination gave me a nice blue look that highlighted the purples too.. but not purple like solely VHO tanks.  I think I'm going to miss the awesome color.  Since I already have the fluorescent Retros, I could use a single or 2 of them for enhanced color with the metal halide if necessary.. but I would like to keep the utilities down by just going with Halide if possible.  I plan to have a mixed tank...I love mushrooms and other softies, I have a frogspawn and Kenya trees, but I am taking a liking to more SPS corals. So here are my questions.. 1)  What would you suggest for my 20" deep tank x 4 ft long...(2) 175W or (2) 250W and why? <I would go with two 175's which gives you 4.6 watts per gallon, a good ratio for most corals and anemones.> 2)  If I went with the (2) 175Ws and added 1 VHO or 2 T5s for color, would that be suitable for growing SPS? <Yes> 3)  If I had to run (2) 250W halides, I would opt not to use the fluorescents...so is there a nice spectrum bulb that can be run without fluorescent supplementation?  A couple of bulb examples would be helpful.. maybe a couple of your favorites? <The 250's would be a little overkill and would add to water temperature problems.  20K bulbs (175's) have a nice blue accent.> 4)  If I ever went up to a 90 gallon tank (24" tall) would 175Ws work, or would I definitely need to go to 250Ws? <A 90 gallon tank really doesn't increase your livestock capacity since the surface area is relatively the same.  You would be much better off going to a five foot tank.  And, yes, you would probably need the 250's, and again adding to water temperature problems.> Thanks for your help...-Cody <You're welcome.  James (Salty Dog)> Forgot to add that my MH bulb will have to be about 8-9" off the water due to my canopy.  I'm not sure if that factors into your decision or not. <Not much Cody.  James (Salty Dog)>

Marine lighting 8/28/05 Hi Bob, <James today> I would like to know what you think of the new Coralife 150 watt halide that mounts onto the tank. It is a 20 k bulb, I was considering putting it on my 42 gallon hex tank to keep mushrooms, polyps and possibly a bubble anemone. The tank already has two true percula clown's, a four lined wrasse, and a golden angel, 30 lbs of live rock and a CPR refugium with skimmer built into it. this is a hard tank to get multiple lights on because of the dimensions . What do you  think is the best lighting for this type of tank?  What are the pro's and con's of  halides or my other choice pc's, thanks Ron from R.I. <Ron, the 150 is a nice light, but in your 42 hex I'm afraid it wouldn't be enough to support corals and an anemone.  It is just giving you a little over three watts per gallon and we should be looking a four watts+ per gallon, especially being the hex is a fairly deep tank.  Hex's are really not a good tank for keeping corals, etc for this reason and the fact that the surface area is very small in relation to tank volume.  James (Salty Dog)> Halide bulb selection 8/18/05 Hey guys,  I have a 150 watt metal halide bulb (10000k) it looks too yellow for my tank. I am going to purchase a higher k  I would appreciate it if you would tell me the best bulb for my double ended fixture. I was looking for something that's not all blue but has a nice tint to add a bit of deeper water look. List 13,000k Geissmann MegaChrome 14,500k Geissmann MegaChrome 20,000k AquaLine 20,000k Geissmann MegaChrome any other bulbs in the blue coloration and are 150 watt you know of that are better please let me know. Thanks for your time.  <Aaron, the 10K bulb shouldn't look yellow at all.  Wondering if the bulb is defective or you have an excessive nutrient problem making the water look yellow.  James (Salty Dog)> - Aaron

Too much light? MHs 8/9/05 Hello crew, I have a 125g (72Lx18Wx22H) salt water tank w/fish only. I plan on a reef tank w/light loving corals. I bought a used dual 400w MH kit at a great price. I know this is too many watts for the depth of the tank, but I couldn't resist for the price. So can you please tell me what I can do to make it work. I read that you can use window screen in layers but wouldn't this melt? <If it's too close, yes> Can I move the lights higher than normal? <Yes> The tank has two plastic braces at the top, how hot will these get, and can I cover them with a heat shield type of cover. Thank you for any info.   <No heat shield... but you want to keep at least a foot of space between, and never heat them more than you can stand to place your hand on... You might look into means to "turn down" (through electronics) your 400 watt units to lower wattage (will save you a bundle on electricity costs, as well as not having to walk around the house with sunglasses on...). Contact the larger lighting outfits... maybe Perry Tishgart at Champion... re this possibility. Bob Fenner>  

Re: Clams and Upgrading PC Lighting 8/6/05 Thanks for the response. I am not sure what is available to me so that I can use metal halide lighting with the setup I have. I have a Current Dual Lamp light. Do they make bulbs to replace the actinic and day light I currently have? If they do which one do I replace?<<You're welcome. MH lighting and PC lighting use different ballasts and fixtures so that simply replacing bulbs is not an option. You will need to research MH lighting and determine what is suitable for your tank. Considerations include the dimensions of your tank, what livestock you currently have and what you would like to add, hardware aesthetics (using a canopy vs. pendants vs. fixtures). Also, you will need to determine what MH bulb(s) you want to use. My friend, you have a lot of reading! The good news is that WWM has a lot of information to offer.>> If they don't make a metal halide bulb how do you suggest I add one (I have enclosed a photo of my tank). Would adding a halide light be too much for my corals?<<After determining what MH fixture, bulbs, etc. you are going to use, please search WWM on "acclimating corals to MH lighting" and read through the FAQs. Good luck - Ted>>

New Halide distance over water surface - 8/01/05 Hey guys how are ya all? <Thanks Aaron, we are good, hope you are in good health as well...> I have a question concerning lighting. I have a 29 gal reef tank with 2 Percs right now. I am currently running around 4 watts per gallon of PC lighting. I bought an anemone from my LFS about a month ago because it was looking shabby and they would sell it to my at next to nothing. So now I want to order the Coralife HQI/PC combo fixture. That will give me 9.7 watts per gallon. <150 watt/250 watt? Species of anemone?> I was wondering if I acclimate the tank very slowly to the new lighting will they burn? I want to house a vast array of corals and 4 watts per gallon just wont cut it. I also need to hang the fixture about 6 inches from the surface and was wondering if this would cut back on its efficiency. <Depending on the intensity, I would even recommend raising the bulb 12" and slowly decreasing it an inch every 3-4 days until you reach 6" or so. Do a search on coral lighting acclimation, there's a ridiculous amount of information here.> Thanks for your time, -Aaron <Good luck - Ali>

MH Question - 07/23/05 I was wondering if you guys could give me a good idea of what I should do for my lighting. <<Depends largely on what livestock you intend to keep...but I'll do what I can.>> I have a Oceanic 30 cube that I just want to put my 150 watt Aqua Medic HQI over. <<Sounds fine so far...>> The thing is I think 10K bulbs are too white, and the 20K bulbs are too blue. <<Disagree on the 10K, agree on the 20K.>> I was wondering what bulbs you think are better the 12K, 14K, etc... And out of them what brands you trust to buy from... <<My preference is 10K, but if you really don't like the looks of a true 10K then my recommendation is the Aqualine Buschke 10K bulb (hold on a sec!).  The AB 10K is more "blue" than others (closer to a true 13K) ye still quite "bright", and the AB brand bulb is an excellent product.  If by chance you decide to go with a true 10K, then my recommendation is a Ushio bulb.>> Thanks -- Nathan <<Regards, Eric R.>> MH for 37 gallon set-up 7/21/05 I would love to have suggestions for lighting a 37 gallon tall tank. Approximate measurements (30 long X 12 deep X 22 tall).  I currently have a 3 year old 25 gallon tank with refugium that is flourishing with soft corals and 3 fish (clown, coral beauty, mandarin) with a 130 watt PC from Custom Sea Life.   I "inherited" the 37 gallon with fish included (7 total).  Currently I'm lighting the tank with an old 110 watt PC hood.  I've added a 2-4" sand base - but nothing else.  It's been circulating for 2 weeks.  Enough background - I want to create an environment to house SPS and more light needy corals that I have stayed away from for my 25 gallon.  I love the look of MH and would love to have suggestions.   <A small wattage (no more than 175) pendant...> One obstacle on the tank is that there is a 1" wide black plastic bar in the center of the tank on the top running from front to back.  I'm afraid a bulb in the center of the tank would cast a bad shadow into the tank. <Place the light a foot or so above the tank, slightly off-center> Any suggestions are very much appreciated and welcomed! Thanks - Cheryl <Welcome. Bob Fenner> Help with DIY MH... 7/21/05 I have been thinking of getting a metal halide system, but do not have the money to actually buy one... so what I've decided to do is make my own using some existing equipment i am currently using. First off, I have a 130W Odyssea PC (Jebo) with one 12K bulb and actinic bulb. I've looked at many metal halide systems and have noticed they had this running as well. So, my thought would be to combine these with a metal halide. i would like to first ask everyone where to start when looking into a DIY metal halide system. <OzReef.org> So far, I know I need 12gauge wire, <Mmm, maybe something thicker...> a ballast, the DE bulb, and two connectors to each side of the bulb. My question would be what to look for in a ballast (what brands), what's the difference between the 20k bulb vs. other bulbs, how many watts should i need for a 20 gallon tank. I've never done a DIY for anything, but the price for a prebuilt one is ridiculous.  I would like to try and incorporate the ballast into a section I've found that's empty inside of the PC. I want to try to put the bulb in the center of the entire thing beneath the two PC bulbs also adding some aluminum reflectors to it. Would I need to take off the acrylic sheet that blocks the light bulbs from everything else? Thanks for the help. <... well, first off, I would not use MH technology on such a small volume/system... second, know that these units can be very dangerous... exploding lamps, UV burns, fire... I strongly encourage you to look into boosted fluorescent lighting instead. This is all posted over and over on WWM... Bob Fenner>

Re: HQI recommendation 7/19/05 Ok, I read about it, and now I have more questions.  My tank is 48x15x15 (about 50 gal) is not too deep, so with 330 VHO watts I think is not mandatory the MH for the less demanding anemones... quadricolor? <A good choice> I just bought 3 lamps to change the old ones (1 white actinic, 1 blue actinic and 1 Aqua sun all from URI, 110w each one) Is this right? <Your choice/s... actinics are more for show than go... more aesthetic than functional> if the quadricolor is not a good choice under this scheme, what anemone you think will respond with this light? Greetings. Carlos Rafael Díaz Rivera <Sigh... please read here: http://www.wetwebmedia.com/marine/inverts/cnidaria/anthozoa/anemonelightngfaqs.htm and the linked files above. Read. Bob Fenner>

Metal Halides - 2 150's on a 90 Gallon 7/16/05 As I'm still in the setup stage and have time to plan, I'd be curious how you folks would come out on the following:  Specifically, how high would you mount two 150 MH's over a 90 gallon (standard 48x18x24). <About a foot above the actual water>   I plan on soft corals, and perhaps a few Acropora high up in the tank.  I'd say my house in the summer ranges from 72-74, maybe 75 for a few hours in the nastiest part of Tulsa summers which hit a solid 100F.  Just doing a test without water, I can really feel the heat pour down, primarily just directly down below the halides.   <Oh yes> Would your answer change if I was to place glass over all or a portion of the tank? <Mmm, no> How about just some glass (in addition to the glass tank brace) just below the halides? <Again, no... I would elevate the MH a foot above all regardless... for heat and light spread reasons> I realize the issue of aeration, but would a glass canopy be a bad idea to deflect heat (or at least deflect it so it can be washed away by a fan) inasmuch as there will be a sump with good air exchange there? <The glass unfortunately will do more... particularly changing the shift in spectral composition and blocking light penetration> I want to be able to avoid a chiller.  Surely that is doable with either fans blowing on a sump/refugium and/or through the canopy.  Btw, the light fixture is a Sunpaq Outer Orbit, so it has some built in fans.  Still, the heat comes down as noted above?  Thoughts? Thanks very much!     <Please read here: http://www.wetwebmedia.com/marine/setup/lighting/mhmarfaqs.htm and the other Related FAQs linked above... and elsewhere on WWM re chillers, water cooling... You might want to set the light fixtures up in such a way that they can be adjusted for height, dimmed... timed to be off during the hottest days. Bob Fenner> Cube? MH, heat concern 7/16/05 I'm planning a  26"X26"X23"  tank.  My wish is for single 150 watt HQI  to support a FOWLR  system.  The internal overflow box spans the back, has three 1" bulkheads,  and  two pairs of  3/4" , on the bottom of the tank.  (Two for return, and two for a possible future closed loop.) <The return/lines you may well want to raise up to prevent back-siphoning in the event of a power/pump failure> The Iwaki MD-40RX, for a SCWD only return,  The sump's water depth will be below  9" to accommodate a Aqua-C EV-120,  and incorporates a  25 gallon refugium.   I would appreciate any advice, or to know if I'm on the right track, here in Taiwan.  Thank you, for your invaluable service.  I apologize if I have been unclear. -Ryan <You may have heat issues with the size, shape of the main tank, volume of water. Bob Fenner>

HQI recommendation 7/15/05 Hi, my name is Carlos Díaz, writing from Guatemala, Central America. I have a 4 feet long tank, 16" depth, about 50 gallons (2 1/2 years). From the beginning I started using VHO lighting (IceCap 660 3x110) , but I want to change to HQI lighting.  Here in Guatemala it is hard to find anything about marine lighting so, I always bought from USA through internet.   Because my light (VHO) I don't have demanding light inmates, but I want to start with anemones, and maybe true hard corals. I don't have any experience in HQI equipment, then i need your advice in brands of complete sets (hood, lamps, ballast) in order to decide what to buy.  i think because the depth of my tank a couple of 150w x 10k+ will be ok.  maybe you can help me. greetings. Carlos Rafael Díaz Rivera <We have much to share on the topic. Please begin reading here: http://www.wetwebmedia.com/marine/setup/lighting/mhmarfaqs.htm and on to the linked files at top. Bob Fenner>

Metal halide height above water 7/14/05 Hi. Sorry to bother you guys again, but I couldn't find the answer I needed on your online files. I'll be quick. I have a 92 gallon saltwater corner tank that has a 24" water depth. I have a 192 watt PC unit with a 96 watt 10000K and 96 watt actinic blue in it. When I purchased the tank, I had to ask about why my glass cover kept cracking, and you helped me out and now, no more cracked glass. Thank you so much!! I was cracking up dealing with all of that!! <I am surprised that pc's produced enough heat to cause the glass to break, but I am glad to hear that you fixed it!> Well, I wanted to upgrade my lighting and I am planning on purchasing a 175 watt double ended 20000K metal halide with 2-18 watt actinics in it. I want to use it with the PC I already have, however, I do not want more cracked glass. How high should it be hung over the water? The PC is about 3 or 4 inches above, and no canopy is used, just the glass cover. <I am curious about why you use the glass cover.  You would probably double the amount of light reaching your corals simply by removing the glass cover.  I definitely would recommend removing the cover if you are going to use a halide.  The glass will likely get quite hot, so your risk of cracking it is high.  Also, you will not be getting the full benefit of the upgrade if you are blocking light with the glass.  Also, a double ended fixture will have it's own glass cover (which must be used!), so your tank cover will be redundant.> I keep my house well air conditioned, around 74 degrees in the summer. Will I need a chiller? I like to keep the temp in the tank 76, but don't care to set it a little higher. <76 is pretty cool.  I try to keep my tanks close to 80, but they often get as high as 85 in the summer (not necessarily recommended!).  Another benefit to removing the glass cover is that the additional evaporation will offset the increased heat from the halide.  If you remove the glass cover and keep the ambient temp at 74, you should not need a chiller to keep the tank at or below 80.> Also, will the lighting combination I will have be way too blue in color, or will it look okay? Thank you so much, and maybe I will leave you guys alone for a long time after this one. Christy  <This is a very subjective question.  I personally find the combination of most 20K lamps with actinics to be unnaturally blue.  Try to see others tanks and replicate the lighting on the tanks you like.  Best Regards.  AdamC.>

Metal Halide height above water follow up 7/20/05 Thanks for your reply, but now I have further questions. You asked why I use the glass cover and it is mainly because I don't like the mess it makes when the tank is uncovered. My water return causes quite a bit of turbulence on the top of the water, which causes these tiny, tiny bubbles to jump straight up, coating everything with salt spray. As I mentioned, the corner tank does not have any type of canopy, so there is no way I can hide salt spray. <The problem of salt spray should be easily solved.  I run a 92 gallon corner tank with 1500gph+ of circulation with no salt spray problems.> Is there no way I can purchase a metal halide and still use a glass cover? <You can run the halide with the glass cover, but the glass cover will cut down on the amount of light that reaches the tank, especially when the glass is fouled by salt spray.  Keeping the covers also makes it more difficult to control heat.> As far as gas exchange goes, I use large bubble makers, and I run a protein skimmer 24-7. <Ah Ha!!!  The bubble makers are probably unnecessary, especially with a skimmer and strong water movement.  They are probably the source of 99/9% of your salt spray.  These can almost certainly be safely eliminated, allowing you to remove the glass covers.  The loss of the bubblers will be made up for by the amount of fresh air reaching the surface of your water.> As far as corals go, I don't have any yet, because I feel my current lighting is insufficient to sustain them, and I don't like to buy things I know I can't keep alive. The main things I am hoping to have are a few BT anemones and maybe a few other corals like hairy mushroom coral, Plate corals, and polyp corals with similar light requirements. Can a BTA live under my current lighting conditions?  The major thing I want is a bubble tip anemone. I just feel my tank is a little dark and could use the boost, and who's going to complain about glitter lines? <BTA's can be kept under fluorescent light if you have enough and there is no glass cover.  Halides are definitely recommended.> I do already have live rock and fish, snails, crabs, and shrimp. I am just totally confused now. I was supposed to get the halide for my birthday and now I don't even know if I can use one if I do. Please help me. I can hang the light any distance from the glass cover, or could you advise on how to not use a glass cover without having a huge mess on everything? <I didn't mean to discourage you from using a MH light.  I only wanted to point out that you will not get the full benefit with the glass cover in place.> I am willing to remove it, as long as it doesn't need wiping off in an hour. I don't mind wiping it weekly or every couple of days, but don't want to do  a huge cleanup every hour, and the way it is now, I would have to wipe it off every hour for it not to look gross. <See the comments above about the bubblers, and your wish will be granted!> I value your opinions at WWM and consider them the bible to saltwater fish keeping. I am sending a picture of the tank to help you help me. Thanks so much. Christy <Thanks for the very kind words.  Glad you have benefited!> P.S. The reason my glass had broke before, is I was placing it directly on the glass, not using mounting legs, which I didn't know I needed. It is funny now at how stupid I am at this great hobby. Everyone that knows me thinks I am obsessed with it. They are probably right. See ya.  <I don't see any indication of stupidity.  We all make such mistakes.  Enjoy your (all of our!) obsession!  Best Regards.  AdamC>  

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