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FAQs about Canopies, Tops and Housings for Lighting for Marine Systems: Rationale/Use

Related Articles: Canopies, Covers & Lighting Fixtures, Marine Light, & Lighting, Moving Light Systems, Marine System Components Used Gear

Related FAQs: Canopies 1, Canopies 2, & FAQs on Canopy/Cover:  Design/Engineering, Construction, Sealing, Reflectors, Fans, Wiring, Repairing, Marine System Lighting, FAQs 2, FAQs 3, Actinic Lighting, Metal Halide Lighting, Fluorescent Lighting, Compact Fluorescent Lighting, Small System Lighting,

Mmm, let's see... to prevent livestock from leaving... reduce evaporative water and heat loss... give light fixtures, fans and such a place to hang... get rid of light reflecting, filtering, obstructing covers... to prevent you and others from going blind... to reflect, re-direct the bulk of light energy into the actual system... to "finish" the look of the overall system...

Glass top or not?    8/9/13
Dear Crew,
<Hey Karen>
I have had a 46 gallon reef for over five years. This website is fabulous and I read it almost daily. I keep mainly softies, with a Flowerpot hosting 2 Percs and a large clam as well. My filtration system is a Tom Rapids Pro with ChemiPure Elite instead of carbon and a CPR large hang on back fuge with DSB, Miracle Mud and a variety of macro algae. The fuge lighting is on a reverse schedule from the tank's 36 inch Aquatic Life 4 bulb t5 fixture (2 10,000k and 2 20,000k bulbs). A few months ago, over the course of a week, several fish jumped out, so I had a glass top made. I replaced the fish, but my corals are looking a little worse for wear - the clam is losing color after being in the tank 4+ years, polyps are not extending, etc. since putting the top on. Light bulbs are changed annually. I know there are thoughts for and against tops on tanks, but I am about ready to take mine off again. I never figured out why I had so many jumpers and I
feel like I may have to choose between my fish and my corals. Any thoughts or suggestions?
<Mmm, yes; I'd take off the glass top; either make or have made a screen mesh (all plastic material) to keep the fishes in, and do the top offs w/ just water... to keep spg. about right>
Thanks very much for all you do,
<A pleasure to share; assist you. Bob Fenner>
Re: Glass top or not?

Pardon my ignorance, but how might the top be negatively affecting the corals?
<Oh! Two ways principally. Photonic energy changes (shifts to longer wavelength) when passing through media (glass, acrylic) of higher optic density (than air); and secondly reduction overall due to reflection and any "dirt", salt, scratching. BobF>
Re: Glass top or not?    8/9/13

<Ms. K>
What a fast reply! Do you think the glass top is related to the coral's decline? If so, how?
<Could be a contributor of some significance; from light shift, reduction, heat retention. B>
Re: Glass top or not?     8/13/13

Thanks so much for the fast reply! You all are awesome. The reef is already looking better since removing the glass top. The Clam especially looks much better. I also removed some pulsing Xenia that had spread to the Clam's rock. This probably helped as well. I didn't think of Xenia as being aggressive, just invasive like a weed.
<Ah yes; keep those pulsing corals "cut back", contained>
Lesson learned! It was without a doubt irritating the Clam even though the weren't yet touching. Thanks again.
<Thank you for your follow-up. Bob Fenner>

MH question 2/11/12
Hi Crew,
<Hello Ragu>
Can MH pendants be mounted on the aquarium top? I mean just placing in on the aquarium braces?
<You could if there is no glass cover on the tank but I would not recommend this, too risky, a good chance the fixture may end up in the tank.>
I have a Arcadia series 3, 3 * 150, I am using it for a 6ft L * 2.5 ft W*3 ft height. The thing is I don't have a canopy and the ceiling is now covered with plaster ceiling thus I am not able to find mount points to hang it. Further more my aquarium comes with a cover. My braces are 12.5 mm thick, I am wondering if it can withstand the weight? The lamps can clear the braces thus the light is not hitting on the braces.
<I suggest you go with a pair of pendant mounts which can be screwed to your cabinet and can be adjusted for height.  Take a look here.
If you're handy, you could even put together something similar in design.>
<You're welcome.  James (Salty Dog)>
// ragu

Re: 30 gallon cube FOWLR setup, top  11/2/11
Quick question,
<Sure, Rudy>
Since I am using a canister filter and also a glass oceanic top for my oceanic 30 gal cube tank, will there be enough space around the lid for adequate gas exchange? It's a pretty snug fit.
<Gas exchange won't be a problem.>
I will also have live rock in the tank.
<Always a good thing.>
I can leave the back plastic of the oceanic glass top off,

<No need to leave back plastic off for gas exchange, but you might find that during the summer months the tank will heat up b/c of the glass lid. I cut out and cover our 90 gallon tank with a heavy plastic mesh from Home Depot; some people use egg crate.>
but will my fish jump out, especially if I get a micro bristle star fish?
<Best to keep lid/cover on unless you are using an alternate cover>
<No problem. Michelle (Fichecake)>

Metal Halide Distance from Water Level (a too-tight fit) -- 12/27/10
I am thinking of adding a 250W metal halide fixture to my 180 gallon tank that is 30" deep.
<<MH is my fave lighting solution 'for its flexibility re use of reflector types, bulb color and positioning of the bulb (distance from water's surface)'¦and overall aesthetic value (shimmer). Nothing like a good 'single point-source' lighting option, for me>>
I have limited space above the water level due to an existing canopy.
There is a total of 5-1/2" from hood to water level, leaving only about 3" from the intended metal halide bulb to the water level.
<<Too little space>>
I have existing 4x96W power compact fluorescents. Thoughts?
<<Even were we to assume that an unshielded (Mogul base 'no ancillary UV shield) bulb would not get broken from incidental splashing of tank water on the hot glass tube, both unshielded and shielded (DE'¦used with ancillary UV shield) bulbs will have their output heavily obscured by dried and 'baked-on' salt/calcareous mineral buildup on the bulb/bulb shield very quickly at this distance. Bulbs in such an enclosure and in such close proximity will also transfer much of their heat energy to the tank -- often problematic in of itself. Such confined space also means you'll need to use a small/shallow parabolic reflector, or worse, a simple flat piece of reflective material -- neither of which will maximize the efficacy of the 250w bulb -- something you may need in such a deep tank, depending on the Zooxanthellate animals you keep/wish to keep. But even if light intensity is not an issue here, this hood is just too 'tight' for Metal Halide lighting. One option, if you're willing, is to cut openings in the top of the hood and mount good reflectors 'atop' the hood. Or better yet, dispense with the hood and mount quality MH pendants over the tank. But'¦ If modifying or removing the hood is NOT an option then I would look to VHO or T5 lighting, or stick with the afore mentioned PC lighting, for use within this canopy>>

To Cover Or Not To Cover; That Is The Question -- 12/16/10
Hello to all with the crew,
<<Hiya Beth>>
Haven't written in a while what with one thing and the other but I've a few questions.
Question 1: I have been running Power Compacts (2 10,000 K daylights and 2 Actinics along with blue LED's) on my 125 gallon (6 foot) reef tank for years with no issues however, the colors of corals I can keep seem to be limited to green or tan and random purples.
<<Hmm'¦ You don't give the wattage, but even if these are 96w PCs, I expect this tank could use a bit more, regardless of the stockings 'and in the 10,000K range versus Actinics>>
Any other colors I get brown out. Reading multiple articles has led me to wonder if this is related to the high nutrient levels I maintain (deliberately as this is a lagoon type set up), which would contribute to a higher Zooxanthellae population per coral
<<One of several factors to consider>>
or to the fact that I have a double barrier between the lighting and the tank (moisture protecting plastic strip below lights and a glass canopy on tank to reduce evaporation).
<<Another contributor>>
Since both barriers can reduce UV lighting,
<<Indeed 'along with total output across the entire spectrum>>
and corals color up as a protection against UV light,
<<A factor, yes 'but in of itself, not the 'whole story' re coral coloration>>
would it make sense to remove one or both of those barriers?
<<In my opinion 'yes. Removal of the 'plastic strip' will increase light penetration. Removal of the 'glass canopy' will increase light penetration and arguably, gas exchange>>
Do you think this would increase the colors on for example, my Acans or Favia? (both a rather bland grey or tan with color only at the oral disc)
<<Can only help in my opinion, considering the type and intensity of your current lighting system. But as eluded earlier, lighting is not the sole answer to coral coloration. As you mentioned, nutrient control can be a factor 'along with nutrition/feeding and the availability (lack of) of key amino acids. Water chemistry is also a player here. An imbalance/shortage of bio-minerals can also cause some corals to lose color/intensity, in my experience>>
Question 2: I have an elegance coral who appears to be doing quite well but I have questions related to its feeding. I currently feed a little bit of whatever I am feeding the fish. This could be Formula 1, Formula 2, Plankton, Marine Cuisine, etc.., quite varied and something different every day but not much of it. I thought that this would be a bit more along the lines of how they eat in their natural environment but noticed in your posts frequent suggestions for larger, meatier feedings twice a week or so.
<<This is mainly if the coral 'is not' getting what it needs from your daily feedings. If the coral is feeding and doing well now, I see no need to change your methodology>>
Since I do maintain a high organic load (no skimming and very little true filtration, just random water movement), and since it does appear to be doing fine, should I just continue my current practice?
<<Sure 'for the reason just stated>>
I do 30% water changes every 3 weeks or so and am not concerned with over feeding so much. The elegance, along with the Wellsophyllia, Acans, anemones, and Favia, appear to eat everything I give them and never regurgitate so I thought I was doing ok.
<<If this is the case then yes, I would agree>>
Other possible contributing factors:
PH: 8.3 ish (varies from 8.1 to 8.3
Nitrate: 10-20 ppm
<<Some Nitrate is important to both health AND coloration. These levels are likely fine for the biotope/livestock you have, though striving to keep it toward the lower end of this range may prove best>>
Alk: 9 to 11 dKH (I do have to buffer every week or so).
Calcium: 400 avg.
Phosphate: 0 but using API and have had other forums state a not very accurate test kit
<<Might I suggest a Salifert or Seachem kit then. Or if you want to get really accurate, one from Merck or Hach>>
Temp: 78
SG: 1.024
<<I would raise this to NSW levels (1.025/1.026)>>
Thanks as always for your advice and work.
<<Happy to share>>
<<Poor coral coloration is often a combination of factors in my experience. Try 'clearing the path' so to speak, for your lighting as discussed 'and maybe lower those Nitrates just a bit (add a skimmer or some chemical filtration) and see what that does. Adding a couple more 10K PC bulbs would also help, in my opinion. You could also look in to some of the amino acid supplements available 'and/or add some Selcon to your feeding regimen. Eric Russell>>

To Cover or Not to Cover 5/30/09
Hello crew,
< Hello >
I'm wondering what your opinion is on using covers on top of the display tank.
< I'm not a fan of them personally but they do have useful applications. >
I had been using a glass cover on one half of my 75g reef tank. On the other half, I had been using a "cut to fit" Plexiglas cover that allowed room for my overflow unit and a small protein skimmer. I don't have a hood and my light sits on legs spanning the length of the tank. I had the covers on for a little over a year. I've recently removed both covers and have been going with an open top. I like this a lot more. The lights look better in the tank, it's cleaner looking and access is much easier. The downside seems to be a big increase in evaporation. Is there anything else I should be worried about with the open top?
< There are a few downsides as well as some upsides to open tops. The increase in evaporation is one downside( This could also be considered an upside. Evaporation helps in cooling water temperatures. A real upside if your having overheating issues.) The types of animals being housed should also be taken into consideration. Some fish are known jumpers and should not be housed in open top tanks. Also, open top tanks are more susceptible to airborne contaminates. The upsides are better gas exchange, less light filtration, and ease of access. I would go with an open top, but only after proper consideration of the mentioned drawbacks. GA Jenkins >

Re: Cyano Control - Glass Tops (Bob, do you really recommend these?- Sara M.)  5/11/09
<Hello Tom>
I want to thank the crew for providing a wealth of knowledge.
<our pleasure>
Wanted to give feedback on my tank condition. My first email was 1/13 or 1/14/09 and here it is May already and I am still combating Cyano but with noticeable success. It is a very slow process but I can clearly see the LR has growing spots of pink algae emerging. I guess like most humans we hope for the quick fix and seem to get discouraged when results are not achieved overnight. The advice I was give was to do water changes which I have been doing 1 to 2 times per week and making sure there was good water flow.
Also changing the activated carbon every 2 weeks and trying to feed properly. Now I am encouraged because I do see results!
<Great! And good for you for being patient and sticking with it! With marine aquarium keeping, it is definitely true that "slow and steady wins the race.">
By the way I have a question. Is it better to have a glass top on the tank or not.
<Glass tops are almost always a very bad idea for marine aquariums. It's difficult to maintain proper pH in a covered tank because you just don't usually get nearly as much gas exchange as when the tank is left
I used to have one on my 46 bow with the compact fluorescent light fixture sitting on top and it cracked and instead of replacing it I bought supports to hold the light fixture up. For some reason I thought it was better to have evaporation but I was reading The Conscientious Marine Aquarist 2nd edition and it was mention to have a top.
<Really? Can you tell me what page? I'm surprised Bob would recommend such... and don't remember seeing that part.>
<<A good idea in most cases to have some sort of "top" to reduce the very common incidence of life leaving a system.... but if glass (or acrylic) is used, very important to keep it clean (for light transmission mostly)... the salt spray, splash removed, algae off... RMF>>
Best Regards
Sara M.>

Re: Cyano Control, tops  05/13/09
Hello Sara:
I read it on pages 36 (2nd column 1st paragraph), 40 (1sr column 2nd paragraph) and page 55.
<Ah, thanks... Bob recommends them to prevent salt creep and to keep animals from jumping out (these are obviously big concerns). But ultimately, it comes down to a personal choice. I don't like glass or
acrylic tops because they need constant wipe downs and prevent gas exchange. To keep animals in and prevent salt creep, I prefer canopies (if you can afford them, or are lucky enough to have a friend who can build them).>
Then towards the end of the section on page 55 discussed is the need for gas exchange.
My tank is a 46 bow tank with a canister filter (Fluval 404), hang on Remora Pro protein skimmer and 2 Maxi Jet 1200 pump for circulation.
Should I have a top on the tank?
<Please see above... you should have some methods/ways to ensure animals don't jump out, and to control salt creep. How you do so is up to you though.>
Sara M.>

Cover Or Not 3/4/08 Hello all. <Hello Matthew.> I have just been reading up on aquarium covers and want to take mine off. I am willing to top off daily because of this. <Are you also willing to risk losing fish. Many fish do jump, especially if startled.> I currently have a 55 gal tank with 130w PC lighting. It is a Corallife Aqualite. There is also a piece of plastic that slides in under the bulbs on the light fixture. I am going to have the adjustable mounting legs for the lighting, so this will raise it off of the surface of the water about 6 inches. My question is, should I remove the plastic insert from the fixture as well as the glass cover? <No, it is there to protect the lamps and yourself.> I am just trying to improve the quality of lighting as much as possible for the lights that I currently have. Thank you all in advance for the wonderful job you do daily for all of us. <If the glass canopy is kept clean, very little light intensity will be lost.> Thanks <You're welcome. James (Salty Dog)> Matthew

Fish Jumping  9//15/07 Hi Folks - I hate to keep bugging you guys, but it seems not many people out there are as knowledgeable and DON'T try to sell you something. <Oh yes...> I have a very peaceful 50 gallon tank (I have a 125 that it is moving to as soon as the NO3 comes down). Occupants are: 5 Chromis Viridis, 1 Nemateleotris magnifica, <I'd have two> 1 Salarias fasciatus, 1 Synchiropus splendidus, 1 Zebrasoma veliferum, <Needs more room> 2 Lysmata amboinensis, Several hermit crabs, Nassarius snails. There are also assorted peaceful soft coral. I have approximately 80 gallons of live rock and about 4" of fine sand. Up until this week, the Red Firefish numbered two and I also had 1 Ecsenius bicolor. There have been no fish additions to the tank since early-July. I came home on Tuesday night to find one of the red Firefish on the floor by the tank well dried out. <Very common... Microdesmids are accomplished launchers> I have egg crate on the top of the tank, but there are sections cut out where chords and various things come out. I had seen the larger Firefish sometimes chase it, so it was not a total shock. Tonight, though, I came home and the bicolor blenny was also on the floor. Now, I've had the blenny for over two years and he was actually one of the more aggressive fishes in the tank. When I went to pick him up, he started flopping around, so I quickly threw him into a net breeder in my quarantine tank. My questions are two: 1) Is there anything I can/should do to help the bicolor? <Hope> He's in the net breeder and there is subdued lighting in that tank. He's breathing fairly heavily, but steadily, sitting up on his pectoral fins, but doesn't swim much. If I move the breeder, he thrashes about, so he's still feisty and capable of swimming. He hasn't eaten anything (tried feeding him Cyclop-Eeze and live brine). I'd like to save him if at all possible, but recognize that it's not likely. 2) The water parameters in the 50-gallon are near perfect. Ammonia and NO2 are undetectable and NO3 is usually <5 SG typically around 1.023. I top off with fresh water daily and do a slow drip of Kalk every other night. Nothing has changed about the maintenance of the tank, so I'm at a loss as to what could have made two fish jump in a week. Particularly since it's really a quite peaceful tank. Please let me know. And, as always, thanks so much for your help! Thanks - Wes <Tape over those openings... Bob Fenner>

More scissortail goby questions. Want To Stop Fish From Jumping But Worried About Sealing The Tank Up 'Too' Tightly -- 07/30/07 Thank you for helping me with my Scissortail Dartfish question (I'm the one whose mated pair of Scissortails seemed to be having a fight.) <<Hi Laura...I don't know who helped you before, but I'm certain they were happy to do so>> The good news is that they did indeed get over it on their own, and lived together happily for another week or so; the bad news is that we didn't have the tank covered well enough and came home to find the larger of the two dead on the carpet. :-( <<Unfortunate... And difficult to prevent... I've had Bartlett's Anthias jump right through the ½' squares of plastic 'eggcrate' mesh>> If you could answer a couple of questions related to the aftermath of this sad event, I'd be grateful: <<I shall try...>> 1) We got some clear acrylic and cut it to exactly match the top of our fish tank, so now there are only small holes around our tubes and wires and so on. This should prevent any future deaths by jumping, but we're a little worried that it's also blocking the flow of oxygen. <<Proper/efficient gas exchange is my worry as well. Do ensure lots of vigorous water flow within this tank>> We have a protein skimmer, <<Ah...a big help re oxygenation>> a power head, and the pump outtake breaking the surface of the water, but all of this action is under the acrylic cover, and it seems like it could just be recycling de-oxygenated air. <<Not a worry if the skimmer's air intake is outside the tank...if not then perhaps you can connect/run a tube to the outside>> Is this an unnecessary worry, or should we do something else to our system to improve the airflow? <<Adding a sump, and if possible, an in-line refugium, will provide many benefits to include improved oxygenation of the system and expelling of accumulated CO2>> 2) We want to get a new scissortail for our bereaved widower. Is there anything special we could/should do in either selecting or introducing the fish to improve the chance of their bonding with each other? <<I don't think it will be much of a problem as this species seems a bit more tolerant of conspecifics than some of the other Dartfish species. Actually, I suggest you keep a small 'group' of these fish rather than trying to 'pair' them out. A small grouping (5-7) should get along fine and will be more natural/make the fish more comfortable and less likely to hide...and as long as they aren't being harassed/chased by other fishes in the tank, having a small group 'may' reduce their tendency to jump>> Our surviving scissortail seems to be very stressed on his own (he's gone back to diving under a rock when he sees me coming, the way he did when I first brought him home a month ago.) <<Indeed...needs more of its own kind around>> We bought the previous pair from the same tank, so they got along from the very beginning without our having to do anything. Thanks for your time and attention, Laura <<Happy to assist. EricR>>

Light covers and marketing Hi, First I'd like to praise your site as having an unbelievable amount of information on it!  It's wonderful to see, and has given me endless reading material. <very glad to hear it> I plan to buy a 75G Oceanic Reef Ready, with Standard Oceanic Canopy, and would like to purchase a Hamilton 4X96 retrofit kit, compact lighting system.  I have read that Mr. Fenner (and some others) advocate removing any glass covers and using egg crate if anything, instead.   <agreed for most> Having experience with optics from a former career, I don't doubt that there is a lot of truth that this practice can be beneficial to maintaining light intensity and spectral purity, so I like to idea and want to try it. Here the question: When I called Hamilton to get some specifics, they insist that this lighting system will require a plastic (I'm assuming plastic) cover, or shield for the light, if no glass top is used over the tank.   <my first experience with Hamilton was about a decade ago. I ordered a light system and wanted to opt out of the plastic lens. They said they didn't recommend it and could not guarantee the fixture if I did. I asked if I could just use a piece of Plexiglas on the custom canopy I was building instead... They restated that they did not recommend or guarantee it. So I bought their overpriced  "special" lens to keep my guarantee and guess what arrived at my door? A rough cut piece of Plexiglas (chips all along the edge) with the Plexiglas paper still attached. I trust that they have improved their tactics since then... but the memory lingers. For what its worth :) > My question is...is this necessary to prevent damage due to condensation as they say, <there is definitely some truth to this if your hood is not properly ventilated (and it should be)> <and if so, won't using their shield defeat the purpose of removing the glass cover?   <correct> Is there any truth to the theory that condensation build-up on the lights will cause problems, or are they just trying to sell me a $4 piece of plastic for $40.00?   <I feel that I got misled as you have suspected> The kit itself is fairly cheap, $399.00. Above all else, I don't want to take the chance of burning my house down! ; Any advice you can give me would be greatly appreciated. Thank you, Eric <since you are not building your own hood, but buying commercial... I would hope that they have designed the fixture with adequate ventilation. There is as much or greater of a concern for splashing and salt creep on the bulbs if you neglect a weekly wipe down. The condensation is easily prevented (muffin fan). Best regards, Anthony>

Tank cover - filtering MH? 7/30/03 Hello Anthony! <cheers> My today's question is concerning cover for my tank. My tank is completely opened from top and I have a 250W MH lamp hung 30 cm above the water surface. Today my two sons were playing in the living room and a small ball was dropped into the tank, which leads me to the question: If I place a cover, simple glass or acrylic, leaving empty spaces on left and right side to allow aeration, would it be a problem? <it may affect (sometimes for the better... sometimes for the worse) the coloration of some corals by filtering the light and UV through glass. More importantly however... the lack of a concealing or enclosed canopy (as evidenced by the ball finding its way in freely) gives me great cause for concern regarding the naked MH light being seen by you or your family. Human eyes should not be allowed to look at the MH lamp unprotected... do conceal this better my friend as with a hooded canopy> Would it cut on my lights penetration or have some negative influence on aeration?? <the light yes perhaps... but the aeration is little issue of concern. You can inject enough aeration otherwise with good water flow and protein skimming> I would prefer acrylic cover, because it is light and it is does not break easily. However my concern is that acrylic absorbs some lighting. Your input would be much appreciated. <the acrylic is not without problems of its own (warping and discoloring quickly in time). Perhaps a piece of tempered safety glass would be better. Seek as clear and thin (say 6mm or less)> Thanassis, leaving for 10-day holidays. <safe travel and return my friend! Anthony>

Avoiding Reef Jerky Dear WWM Crew, <Scott F. at the keyboard tonight!> I am finally ready to stock my 437 gallon (80"x36"x36") Acrylic Tank with two Hawaiian Dragon Moray Eels, in a reef type environment.  The tank has two openings each measuring 16"x22". My concern is weather to leave these openings uncovered in order to enhance air exchange or cover them with acrylic panels to make the tank "eel proof", as well as control evaporation.  Lighting initially will be a 6 foot custom Sealife ABS Fixture with four 96W P.C.'s.  The tank is plumbed to a 150 gallon open sump and connected to a large Aqua Medic Protein Skimmer.  I would appreciate your advise on whether or not to cover the tank openings. Thanks, Ron Well, Ron, as you have surmised, Morays can slither out and around just about any form of confinement, if they feel frisky. I've even seen them many times, when I was fishing, slither right out of the water to eat fish that we were cleaning on the rocks - an amazing sight to see! I'd opt for a cover of some sort- either the factory supplied acrylic slot covers, or a finer eggcrate over the openings. Either way, you do want to secure them, or they can definitely become "reef jerky"! Regards, Scott F>

-Covering a reef aquarium- Hello WWM Crew. <Good evening, Kevin here> I really, really appreciate the advice you guys have given me in the past. It makes such a difference for someone like me who's just getting started with reefkeeping. <We're happy to help!> The issue I'm struggling with today is what to use to cover the 90-gallon reef tank I'm setting up. I know a lot of people don't cover their tanks at all because they don't want to reduce light for their corals and because they don't want to impede the exchange of gases. <Exactly why mine isn't covered.> These are definitely concerns for me, too, as I plan to keep sps corals. <As do I> But I also have my heart set on including a fairy wrasse in my tank, and I know what accomplished jumpers they are. <Holy crap, we couldn't be in more similar of a situation, I just landed a pair of Rhomboid fairy wrasses who I will not allow to hit the floor.> The only alternative I've seen to using a glass top is eggcrate. <Been there, tried that. I found that it lit up the entire room (light deflecting off the sides) and it would absolutely blind me as I approached the tank. I have also tried this stuff Home Depot sells called 'hardware cloth'. It's basically chicken wire w/ 1/2" squares covered in a green plastic and does not seem to make much of an impact on the lighting situation. Lately I have been doodling some plans for an acrylic frame about 2-4" wide that will fit into the groove in the top bracing of the tank where I would string fishing line through holes space 1/2" apart across each side. You would end up with a nice clear net that would keep fish in and allow for proper gas exchange and light penetration. I would also look into pond netting, as they may have some types that are clear.> My main concern with eggcrate is that it seems like the plastic grid would block a certain amount of light. Do you have any thoughts on that? My lighting will consist of four T5 fluorescent bulbs (100W each) and one 175 MH pendant, all suspended about 9 inches above the tank. In doing a little internet research, I did find an eggcrate product made for photography lighting which is actually supposed to diffuse and slightly intensify the light as it passes through the grid. The individual squares are apparently coated with some sort of reflective material -- possibly aluminum, but I'm not sure yet. Sounds interesting, but it's quite expensive (about $200 for 2' x 3')<Yikes, you're not kidding. Who knows how fast it will degrade w/ the saltwater splashing on it.>, and I'm afraid that the reflective material could be toxic in saltwater. <A possibility> Since the eggcrate would sit right on top of the tank and would likely be splashed from time to time, the toxicity issue makes me nervous. Are there any other alternatives I haven't thought about? <Check out my comments above, that should give you something to go on. I hope my rambling has been of some use, -Kevin> Thanks for your help. Don't know what I would do without you guys.   

Covering Reef Tank Follow-up? >Thanks so much for the advice -- I never would have thought about the glare off the eggcrate.   >>I wish I knew who helped you previously, I'd put this in their folder.  Glad whoever it was helped. >I think I'm going to try your acrylic frame with netting solution.  There's actually a plastics store a couple of blocks away from my apartment that does custom orders.   >>So and so will be glad to hear it.  Marina

-Covering Reef Tank Follow-up- <Wow, looks like you get both Marina and Kevin in this one, I hope you can handle it!> >Thanks so much for the advice -- I never would have thought about the glare off the eggcrate. <Neither did I, that is until I was blinded by it. It also seems to visibly cut down on the light, since the eggcrate is about 1/4" deep> >>I wish I knew who helped you previously, I'd put this in their folder. Glad whoever it was helped. <Me me me!> >I think I'm going to try your acrylic frame with netting solution. There's actually a plastics store a couple of blocks away from my apartment that does custom orders. >>So and so will be glad to hear it. Marina <Do send pictures if you finish it!!! I've yet to start it myself, and would love to see how yours comes out! -Kevin>

-Covering Reef Tank Follow up to the Follow-up- >Will do.  By the way, I'm having some free samples of PVC netting sent to me from a company called Internet (at www.internetmesh.net).   >>Oh, really?  How'd you find this place?  Is it resistant to UV and heat?  This may be a good solution for a LOT of people. >I'm told the "squares" in the netting samples I'm receiving range from 1/4" to 1/2".  If the netting is clear or at least very thin, it may also work well in a frame over the tank.  If it turns out to be good stuff, I'll let you know.  Thanks again, Kevin. >>Absolutely please do.  Marina WWM FAQ Crew <crew@mail.wetwebmedia.com> wrote:-Covering Reef Tank Follow-up- >Thanks so much for the advice -- I never would have thought about the glare off the eggcrate. >>I wish I knew who helped you previously, I'd put this in their folder. Glad whoever it was helped. >I think I'm going to try your acrylic frame with netting solution. There's actually a plastics store a couple of blocks away from my apartment that does custom orders. >>So and so will be glad to hear it. Marina

Re: 75g New Reef Tank Canopy Hey Gwen, Alejandro here again asking you about the lights, probably tired of hearing my light problems, <<Naw. Don't worry about it :) I just wish I could explain things better to you, but this is a complicated subject and requires much research on your part, in order for you to make the proper decision. I hope you will keep reading!>> well I hope this is my last email about this before my purchase, yes I told you I was doing a canopy but if this is not necessary and I can buy an already-made hood with UV protection and everything and all I have to do is raise it some several inches above my tank I can get a piece of wood and raise it 12 inches or something like that would that do it? <<Yep. But you should not need to raise up a ready-made hood. If you are so concerned about heat, you should look into buying hanging pendant-style metal halides. The pendants come with protective acrylic lenses and you can hang them at any height you wish...usually about a foot above the tank. They look great. And if you buy 10k bulbs for your pendants, you will not need actinics at all. Just the metal halides. You can buy 175w, 250w or 400w metal halide pendants. If you don't like pendant shaped lights, there are also rectangular-shaped hanging metal halides, from companies like Giesemann, for example. You can do a web search to find more companies or even mail-order them on the Net. I can't recall any offhand. For a four foot long 75g tank, I would recommend two pendants, 175w -250w each. Again, it really depends on what livestock you plan on keeping.>> Or buying that same kit but in retrofit and making a canopy? Down here its hard to get good things done like you get up there or people you can trust to help you, it's all about the money and getting it out of the way. <<It's like that everywhere...you are wise to ask your questions here.>> And it's my money in jeopardy, not theirs, that's why I look for your help. I am ready to order but just want to know which ones of those hoods will make my life easier: the one that you place on top of the tank like a Perfecto hood but raising it, my doubt is wouldn't the light spread around <<If you raise a Perfecto hood, it will spread around, so don't raise it.>> cause it won't have a canopy, this is probably better than a canopy because I don't have a chiller and more air would pass I don't know, please tell me what to do? <<Don't' raise it, just buy a canopy with a fan built into it, or hanging MH's.>> And is their any difference between the acrylic and the glass in functions of a protector for the bulbs if I get the canopy? <<Most hoods being sold today come with acrylic to protect the bulbs from salt spray, and to protect the fish and coral from UV, clean the covers often to prevent salt build-up from keeping the light from penetrating properly.>> And if  I get the hood it already comes with its UV  protector <<Yes.>> so should I remove the glass cover from  my tank because then it would be open air? <<If you like.>> also the bulbs are 5500 Hamilton's each and I could upgrade them for 10K USHIO each what do yo say? Thanks a lot. <<I am not able to compare either, I have not used these. Perhaps another member of our team can give you this information. Sorry. I DO have experience with Giesemann, though, and they really light up a tank, and make the inhabitants look spectacular. Pricy, though.-Gwen>>

Metal Halide Lighting 12/26/04 Hi, I was just wondering how much light most the anemones need and where they would be placed. If I was to use 150 watts were would I place it???? <It depends on the anemone.  150W metal halide might not be enough for Heteractis Magnifica regardless of placement, but on the other hand, Entacmaea Quadricolor may do fine in any part of the tank.  Do look to "The Reef Aquarium Vol. 2" for good info on specific requirements.> and what is the best Kelvin rating to use with soft corals and anemones??? <This is largely an aesthetic choice.  The animals don't really care.  However, as a general rule, lower Kelvin lamps produce more usable light per watt.  Also, FWIW, the only popular aquarium lamp available in 150w is the Iwasaki 6500k (which is actually mercury vapor).  Most Metal Halide lamps are 175w.> Hi, Also just wondering how much percent of the light is lost if cover glass is used and is that percent left an efficient amount???  Thanks <I don't have statistics on how much light is lost due to cover glass.  It depends on thickness and how clean it is.  Even very clean thin glass will block a significant amount of light, so most reefers choose not to use it.  There are other reasons to avoid glass covers as well...  heat retention, less efficient gas exchange and less evaporation.  If you are worried about fish jumping, consider other options like a high sided hood, "egg crate", etc that will avoid the problems of glass, but will also keep your fish in the tank.  Best Regards.  AdamC.>

Open Top...Open For Trouble? (Concerns Over Open Top Tanks) HELLO <Hi there! Scott F. here tonight!> Whereas many aquariums have ready-made canopies, reef aquariums with  open tops offer many benefits such as better air exchange, evaporative  cooling, better lighting, etc. <True...> Perhaps this is a silly thought, but having an open top allows everyday & inevitable household dust, hair, lint, etc., greater access to enter the system. <Not a silly thought at all...A reality of this type of system.> Chemicals probably are attached to this stuff, so should carbon be run 24/7 in open top reef tanks for airborne contaminants?   Is this really a non-issue? What are your thoughts on this? Thanks James <Well, James, this is something to think about, but I would not be overly concerned about it. Airborne contaminants are a real probability, but with adequate water movement, good filtration, and a little care, there shouldn't be many problems. Common sense around the tank, such as not spraying household cleaners or smoking in the immediate vicinity of the open top will help. Activated carbon and/or Poly Filter media should be used in every system on a regular basis, IMO, as they are excellent at removing a wide range of "bad" stuff from the water. Using such chemical media is a great idea for any tank! Hope this helps! Regards, Scott F.>

Non-jumping Tank Mate for Tomato Clown - Is There Such a Thing? >OK, looking for some help finding a tank-mate for my tomato clown.  >>Oh boy, this should be fun.  >The tank is a 37g with a bunch of soft coral and 2 clams, one squamosa and one crocea.  >>I can tell you already you're going to be VERY hard-pressed to find any fish that won't suffer harassment at the fins of the tomato. Just about any fish is going to jump if pestered the way these tomato clowns can pester. >The tank has been up for over 18 months. It used to house a two-spot hog fish and a Cherub angel as well. Due to temperature issues the tank is open. Unfortunately the hogfish jumped after about 2 months. The dwarf angel jumped about 2 months ago. Very very bummed.  >>Indeed. Consider something akin to fencing around the perimeter of the tank. >Needless to say I'm in the market for a new fish. I plan on covering portions of the tank with some egg crate, but don't want to cover the entire thing for fear of making my clams (mainly the crocea) unhappy. Any suggestions on non-jumping tankmates? I've been thinking about a canary wrasse, a six-line wrasse or a royal Gramma? Thanks, - Matt >>That's really tough when you're considering wrasses - they all have a tendency to get going really fast and then WHOOSH! Uh oh, crispy critter. With that tomato, I would not go any LESS aggressive than a nice, stout Pseudochromis species. You really need to stay with fishes that will not grow large, yet not be timid as well. Stick with animals that prefer rockwork, rather than being benthic or open-water swimmers, this will reduce competition. And, as I said, consider "fencing" instead of directly covering, like what some do with Koi. Marina

-A Cracking Good Time- Hi. <Hello> I just upgraded to a 92 gallon corner saltwater aquarium. I purchased a Coralife compact fluorescent fixture with 2-36" long 96 watt bulbs (one actinic, one 10000K) and 2 lunar lights. <That is a good setup> My tank has a glass cover over the top of it. I put my light directly on the tank, to gain the most out of my lighting, due to the 24" depth of my tank. The light itself has built in cooling fans to keep the Daylight bulb from overheating. There is no canopy of any kind to restrict air flow. <Yes but you will have bad results without something to get that overly hot bulb from cracking your glass covers.  there should be a set of legs to hold the unit up, either with the lights or ordered separately.> My glass keeps cracking. I heard it this morning, the first time, after my light had been on maybe an hour. I went to my local glass store and had them cut me another piece, which is 1/4" thick, by the way. I came home and placed that piece on my tank, and by tonight, it is cracking again. <Hehe, I am not laughing at you but rather remembering my personal glass cracking crusades which led me to a glass filled aquarium and a lot of water on the floor... OOPS.> It is practically breaking a line from the middle to the side each time. Do I need to use some kind of legs on my light? The weight of the light CANNOT be what is doing this, for the second time, I rested the majority of the light on the sides of the aquarium. All I can figure is the heat from the light is doing this. How will raising my light up 3" effect the lighting in my tank? I am going to have live rock, maybe a few soft corals, and some anemones later on. Will this work? Why is my glass breaking? Please help... I am going crazy over this. <Yes, you have hit this one on the head so to speak.  The lights have to be elevated in order to not crack the glass.  Your tank will not suffer from the loss of 3" of height versus all the cracked glass you have.  Though do keep the glass as clear as possible or do not use a cover if you can to not limit the light from getting into the water.> <Justin (Jager)>

Fish Jumped (6/13/05) Hi there!! Great site! So far, your help has been more than appreciated! <Glad to be a part of this helpful venture. Steve Allen with you tonight.> There is my question. I had a Chalk Basslet, very active fish, great health, lots of personality and never afraid, no matter what happens! A few days ago, I left the glass cover opened for a few hours (my mistake, I know!) and the Chalk jumped out... <Sorry to hear. I've found a couple of missing fish dried up behind my tank months later myself.> I was wondering what could have made him jump out?? <Impossible to say. Spooked by something. Just happened to jump. Many possibilities.> Water quality is good, ammonia/nitrites: 0, nitrates: ranging from 10 to 20 ppm (little high...), sg: 1.025, temp.: +/-78F, water changes: every week, 5-7%... other fishes: ocellaris clown, royal Gramma (really peaceful, even with the chalk), Yellowhead Jawfish, 2 cleaner shrimps, 1 coral banded shrimp, lots of small inverts, soft and LPS corals... <All sounds fine.> I heard (or read, can't remember) that chalks don't jump out... <Any fish can jump. There is no such thing as a fish that "never" jumps, though some are certainly much more prone to do so than others.> Any idea of the reasons why he "committed suicide"?? <Again, absolutely no way to know. I'd say that anyone who has an open-top tank will eventually lose a fish.> Thank you very much!! If you need more details about my aquarium, please kept me know! Thanks!! Ivan <Consider using a piece of that plastic egg-crate stuff from Home Depot to keep fish in while allowing good ventilation and access for feeding.>

To Cover or Not to Cover, That is the Question - Or Is It? Hello Crew or Eric R., <<Hello, Marina here.>> In Tuesday's (05/24/05) FAQ, someone posted a question  "Wrasse Behavior - Jumping, Freaking And Hiding (Oh My!) - 05/23/05" and in the question the writer stated that he has the top 100% covered because the wrasse likes to jump. Eric R. then responded with <Mmm...not sealed I hope...possibly covered with egg-crate or similar?>  <<Yes.>> My question is why not 100%? Why use the egg-crate? <<Actually, those are questionS, not one question. And the answer lies in a couple of areas of concern for reef aquarists. First being O2-CO2 exchange; this exchange is greatly hampered if the tank is covered in such a way as to create almost a seal. Using something that does not allow fresh air to come across the surface of the water means that this exchange won't take place here. If one is running a wet/dry trickle filter, then it's a non-issue. However, many folks have eschewed this technology in favor of that which does not encourage this exchange. The other issue has to do with heat gain, again a problem in closed reef systems. Glass not only does not allow heat to escape, it creates a greenhouse. Higher heat means lower O2 saturation. Why eggcrate? Because it is chemically inert (unlike aluminum or brass window screening), relatively inexpensive, and very easily cleaned and configured to fit any system. Neat stuff to work with, actually.>> I'm asking because I'm currently running a 100% glass covered 150gal Oceanic RR tank. What am I doing wrong now?  <<Ha! You sound like my father-in-law ("Ron!" "What'd I do now?"), and I KNEW we'd catch you! Actually, not knowing anything else about your setup we cannot say that you're doing something wrong. But if I catch you then I will. <wink> >> Thanks in advance.  Stan <<You're welcome Stan. Now don't let me catch you doing something wrong!  Marina - The One Who WILL Catch You If You're Doing Something Wrong>> 

Lights - 50/50 vs. 10K Greetings. Boy do I need to get to bed! This is such a great time though to get reading in! I have a 90 gal. With a little over 100 lbs. Live rock, some reef safe fish, and good water parameters. Skimmer, UV, sump. I already has some strip lights mounted inside the beautiful canopy my husband made for me. They are two 65 watt PC SmartPaqs (50/50). I have added two 192 watts Coralife PC (1 96 actinic, 1 96 10K). After reading that anemones would benefit better from daylight and not really actinic (did I understand my reading correctly?).  I have been considering changing out the two 65 watt PC SmartPaqs (50/50) for two 65 watt 10K's. This would give more of the daylight that the RBTA likes. I happen to have one of these as of Thursday last week. Seems adjusting well. I have thought I would keep some corals that are easy with medium lighting requirements just to add a little color and interest to the rock. Could you affirm if the Rose bulb tip anemone likes daylight better than actinic?  <Renee', you would be better off exchanging the 50/50's for the 10K's since you have a 96w actinic already. James (Salty Dog)> Thank you. Renee'  <You're welcome>

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