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FAQs about Giant Clam Lighting Lamps, Bulbs

Related Articles: Got Tridacna? A beginner's guide to keeping Tridacnid clams by Laurie Smith, Example Chapter from NMA Reef Invertebrates book, on Giant Clams, Tridacnids, A Brief Guide to the Selection and Placement of Tridacnid Clams by Barry Neigut, Bivalves, Mollusks, Lighting Marine Invertebrates

Related FAQs: Tridacnid Lighting 1, Tridacnid Lighting 2, & FAQs on Tridacnid Lighting: Science/Application, Design/Fixtures, Duration, Quality and Intensity, Trouble/Fixing, Makes/Models/Manufacturers, & Tridacnid Identification, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Placement, Tridacnid Feeding, Tridacnid Disease, Tridacnid Reproduction, Tridacnids 1, Tridacnids 2, Tridacnids 3, Tridacnids 4, Tridacnid Clam BusinessBivalves, Bivalves 2, Lighting Marine Invertebrates,

T5 lighting question Lighting Requirements/Tridacna Clam 2/4/09 Hey gang, <Hi Alex> Quick question regarding T5 lighting, I recently bought a 30" 4X24W HO Sundial T5 fixture, two 10,000Ks and two 460 actinics. Now my question is will this be enough lighting for a Tridacna clam...say a Derasa? <The T5 HO's will work for the Derasa but I would keep the clam no deeper than 12 inches from the water surface.> As I bought a 3" Derasa clam about a week ago and I was told that it should be fine under my current lighting...a Corallife 24" Aqualight Deluxe 130W PC, <I'd use the Sundial T5 fixture you bought. Will be a little more intense than the PC's. The T5 fixture you have is equivalent to about 190 watts of standard fluorescent lighting.> now I have read and reread many times about the lighting requirements and have found very mixed reviews on PC, MH isn't really an option for me, and have found many people having success with HO T5's. <I have heard same, but the T. Crocea does best under MH lighting, but has been kept successfully under T5 lighting providing it is kept near the top of the tank and the fixture is of sufficient wattage.> My tank is a 29G with a Flame Hawk <Tank too small for this guy.> and Purple Firefish, couple of small hermits, sandsifting starfish, and a few trumpet corals, GSP, Duncan coral, and some Anthelia. I know Derasa's can get around 20" but I have a 125G that I could relocate it when the time comes. <That time is going to be long in coming. Under natural/ideal conditions, the average growth rate is 1 to 2 mm per month. In captive systems, likely less.> The clam is currently on the sandbed approx 14" from the light. <Too deep, I'd move the clam up and get that T5 system up and running.> I have even heard of people keeping Crocea's under T5's...is there and truth (long term) to that? <A good article in regards to keeping the T. crocea can be found here. http://www.reefkeeping.com/issues/2007-10/jf/index.php  And Tridacna in general here. http://www.wetwebmedia.com/tridacnidart.htm  and here. http://www.wetwebmedia.com/ca/volume_4/V4I3/Tridacna/artGotTridacna.htm > Tank water parameters are all reef ideal, with the exception of phosphates....8ppm Thanks much, <You're welcome. James (Salty Dog)> Alex

Re T5 lighting question Lighting Requirements/Tridacna Clam And Not Reading 2/5/09 Hey gang (again), <Hi Alex. Since this is a continuation of a thread started yesterday, we ask that you reply with the original thread. In that regard we can see what has transpired.> Ok so the 30" sundial T5 HO 4X24W will work for Tridacna clams depending on type and location in the tank. <Yes.> I have the 29G that currently houses a 3" Derasa that upon James "salty dog" (thank you very much for the advice btw) I have moved <the clam> up to about 8" from the light. Now my new question is, with individual reflectors would this be able to house a crocea clam? <Lighting information/requirements are stated in the James Fatherree link I gave you yesterday. Did you read it?> I read that 10,000K's would be best for a crocea and am just wondering if I switched some of the bulbs what combination would work best for a crocea, or any other Tridacna for that matter? <The choices in Kelvin temperature in T5's are pretty limited right now. To my knowledge a 6.7K, 10K, and 12K are available. In your case I'd go with a 3 to 1 ration of 10K and actinic. The 10K is going to give you a little more PAR value than the 12K.> The crocea is not in the near future but more of a fluttering hope. Or would I need another bulb or 2 on the tank to keep it happy. I want it to be healthy not healthy enough to live. and MH are really out of the question, otherwise I would have them. <All stated in the Fatherree and Got Tridacna link.> thanks again for your expertise, <You're welcome. James (Salty Dog)> -Alex

Lighting for clams Dear Bob, <David D. taking questions this evening.> I have read many marine fish books, your book, "The Conscientious Marine Aquarist" is by far the best, am eagerly waiting for your crew's new book on reef inverts. <It is also the book that got me started in the hobby!> I am confused on the issue of lighting. I have a 55gal reef with 2 clams which I placed on the top part of the tank. Based on watts per gal, I am way below the requirement. <Watts per gallon is a poor rule. Think about it...If two tanks were 100 gallons and one tank was 20" deep and another 30" deep, would they need the same amount of lighting to keep clams or corals?>   My tanks is 36" wide and I use 4 fluorescents, 2 marine white and 2 actinics by Arcadia (a UK company). The lamps are only 18 watts each with 9,500Kelvin. Over the weekend, I changed one marine white to one Coralife white with 10,000 K, also 18 watts. The shop tells me that my lighting is sufficient, I am not sure although the tank is very bright. I read John Tullock's book, "Simplified Reef Keeping", which said that 4 fluores. with 2 white and 2 actinics is enough for a 55 gal reef  tank. I am not sure as your book did not go into very detail on VHOs. please advise. <If I understand you correctly, you have 4x18 watts=72 watts. At this low level color temperature is almost irrelevant. It just isn't enough light to keep a clam alive...Not even close! Maxima clams need lots of light. If you want a watts per gallon, assuming your tank is 18" deep or less, I think you need 5-7 watts per gallon with any kind of fluorescent light fixture. The clam would still need to be in the top portion of the tank. At first the clam will look really large and happy in your tank. Actually, he is swelling to catch as much of the light as possible. Within a few weeks maybe sooner, those beautiful colors will start to fade or he may eventually close up. Either of these events will be the beginning of the end. I would take these clams back and find a new fish store...> The other question is on the brand. I noticed that the Coralife lamps is clearer and whitish/more transparent while Arcadia's is more yellowish and brighter, can you tell me which is a better lamp as Coralife's price double that of Arcadia <I've never heard of Arcadia. But for standard fluorescents, Coralife are good. For VHO? URI.> Thank you. <Your welcome!> Regards, Daniel Kong <Daniel Knop has an excellent book about clams. Also search wetwebmedia.com for more information. Good luck!>

Doing the Fluoro Salsa.. or Was It a Rumba? >Good afternoon! For Bob Fenner and other marvelous WWM FAQ crew. >>Good day to yourself as well.  How goes it? >Recently, my full-spectrum (daylight) fluorescent tube had been out-aged and cannot be used for more. After that, I ask my assistant to buy a daylight tube (I know this is seems to be not wise, because handling an knowledgeable task without supervising can make a wrong choice and creates one more problem) but I haven't much choice, I'm too busy for my stacking homework. >>Understood. >So, when he go home and I see what type of lighting he bought, I see it's a little bit different from the previous one. The light wasn't white-colored, but rather violet hued and seems not too strong to support autotrophic organisms in my aquarium. For example, my two Tridacna derasa clam (sorry -- it's not Tridacna maxima, I realized the species shortly after sending you the email) still exposes their broad mantles, but I'm not sure if the zooxanthellae can tolerate another type of lighting. >>I like T. derasa myself, my friend. >Do you know the type of lighting and is it good for my clams? >>I'm afraid not, my friend.  What you would need is to look for the manufacturer's specifications on the bulb.  I am guessing that you may have what is called a "warm white" bulb, in which case it will be too high in the red end of the spectrum.  You should be better getting a "cool white" bulb, or better yet, possibly calling the shop where your assistant bought the bulb, tell them what you HAD, and ask if they have that same bulb. >And also for my intertidal urchin, Colobocentrus atratus who seems to love the atmosphere and always tries to creeps out of water. I'm afraid if they will develop air bubbles in their test cavity, and slowly dies. >>No, I doubt they would harm themselves in that way. >Should I constantly replace the urchin back to water or just leave it alone? >>As long as it cannot escape from the display completely (and get lost?), leave it alone.  They know where the water is (DOWN!), and will go back when they feel the need. >Thank you very much for previous helpful emails !!  Sincerely, Anargha. >>Alas, I, Marina, cannot take credit for those, but will offer that you are welcome all the same.  Marina

Tridacna Clams And PC Lights - 08/23/05 Hello crew, <<Howdy>> I have been looking into getting some Tridacna clams for my aquarium but I have a two questions.  First, I have a 75 gallon tank (18H, 18W, 48L) w/ 8 65 watt PC lights (4 actinic & 4 WT day) and 8 LED moonlights.  Is this enough light to keep Tridacna clams healthy? <<Tis possible...but I would recommend either ALL daylight bulbs (6500K or 10000K...your choice), or; if you must have blue lighting, no more than 2 Actinic bulbs with 6 daylight bulbs.>> I know metal halide lights are best but with all the money I put into the lights I have right now, I'd rather not have to go get new lights. <<Keep the bulbs "fresh" and close to the water's surface, and go with T. derasa and/or T. maxima and they'll likely do fine.>> Second question, I currently have a brittle starfish in my tank and I have heard that they eat clams. Is this true? <<Not in my experience/estimation.  I have always kept Brittlestars in conjunction with clams...I've never seen nor heard of a Brittlestar attacking a "healthy" Tridacna clam...any perceived predation was likely a result of the star "cleaning up" on an already doomed specimen.>> Thanks <<Regards, EricR>>

New Lighting For Clam - 03/15/06 Hi, guys! <<Don't forget the "gals" here too!>> I always hate to bother you guys but I've done quite a bit of surfing and FAQ searching and, although I think I know which way I should go, just wanted to get a final referral before I change my lighting. <<No worries mate...shoot.>> I currently have 2-96watt compacts for a 55 gallon 48x14x19 tank.  I was thinking of upgrading to a 4-96watt fixture to double my watts in hopes of it being enough light to sustain a T. squamosa?   <<I think you could, yes.>> I have mostly polyps and soft coral.  What do you guys think? <<Worth trying/doing in my opinion.  For the clam's sake my suggestion for lamp type is four 10,000K bulbs.  If you "must" have some actinic (would be for you...not necessary for the animals), then no more than one actinic lamp.>> Thanks again for your time, you guys rule! Sincerely, John Kelley <<Regards, EricR>>

Clams/Lighting    6/26/06 Dear Crew, <Stephen> I am 6 months into my first tank. I am pleased to say that with this web sites help and a lot of reading, it has passed with very positive results and no major issues. <Good to hear.> I have one question for you though. I have a 50 gallon tank, it is 13" to the sand bed. At the weekend I upgraded from fluorescent to MH. I have one 150w fitting rated at 20,000K. I had hoped to get a Tridacnid clam in some weeks or months time, I figured that the clam would do OK at that depth under 150W. Now, after reading more of your site, I am worried about the "temperature" of the lamp. Is my set up OK or do I need to change to 10,000k. I live in Japan and I had asked for 10,000 and they persuaded me to buy 20,000. I am annoyed now. <Don't be annoyed.  Barry and Sherry Neigut of Clams Direct, use anywhere from 10 to 20K in their systems.> Many thanks in advance. <You're welcome.  James (Salty Dog)> Stephen Marks

Clams/Lighting FYI ... more bad code, info.   6/28/06 Crew I recently answered a query re above.  Talked to Barry at Clams Direct on this for future reference, and he feels 5.5-10K is ideal for good clam growth. Regards, James

Clams/Lighting FYI ... more bad code, info. 6/28/06 <Mmm, do you see any prob.s?> Crew I recently answered a query re above. Talked to Barry at Clams Direct on this for future reference, and he feels 5.5-10K is ideal for good clam growth. Regards, James Bob, Don't know exactly what you meant by "more bad code, info". Reason I contacted Barry was because there were photos on his site that he indicated were taken under 10-20K lighting. I just wanted his recommendation on what he feels is the best Kelvin temperature for clams. <It took minutes to fix the code... the info. is in direct conflict with your resp. of two days prev.> Regards, James
Re: FYI Clam Lighting
Exactly, I didn't feel quite comfortable with the answer after I sent it, which is why I contacted Barry at Clams Direct.  Although not entirely wrong, as clams will thrive under higher Kelvin temperatures, just not ideal for anything higher than 10K.  I do strive to be correct in my answers.  Many times I will search for info other than WWM to ensure correctness.  I'm getting there Bob, not perfect or will ever be, but getting there.  Soon, I will be the apple of your eye.  HA!:) Sorry for the trouble. Regards, James <Will post this more complete input. B>

Giant Clams and Color Temperature - 08/31/06 Hello Crew, <<Vince>> I have a 150 gallon established reef with mainly LPS and some fish. <<Ok>> I am considering adding a clam and read they do best under 10,000K lighting. <<Not an absolute...but is a good baseline>> My current setup consists of 2 250w 14,000k MH with 2 T5 Actinic. <<This would be fine.  I have three T. crocea under a 250w 14000K pendant on the substrate in 24" of water (30" deep tank) they are doing marvelous...I don't want to downplay its importance, but it is not always "all about the light">> If I switch to the 10,000k bulbs do I need to acclimate my current livestock to the temperature change? <<Maybe...depending on the PAR output/age of the bulbs>> My current bulbs are only 4 months old. Thanks for your time, Vince <<To be quite honest Vince, I think your lighting will be fine for "any" of the commonly available Tridacnid species.  Placement up/down the water column can be adjusted to suit the differing lighting requirements, though I suspect this to be of little concern.  No need to change the color temperature of your bulbs unless it's for "your" benefit...in my opinion>>

Crocea Lighting 1/9/08 Hello, First off, thank you for answering mine and the thousands of other emails you must get. <Hello, it is a collaborative effort, we do answer quite a few queries.> I have a 125 gallon tank with an attached 30 gallon refugium & 20 gallon sump. One half of the tank I keep open swimming space and the other half I have live rock. Currently I have two 72 in blue actinic bulbs powered by an Ice Cap 660 ballast. I also have a 36 in PC 10k bulb over the LR. I received a Crocea clam recently and would like to upgrade the PC lighting to MH. <Good idea.> The tank is 18 inches deep, but I plan to keep the clam about 6 to 8 inches from the surface after acclimation to the new lights. Would you recommend 175 or 250 watts for this distance? <The 175 will work fine at this distance for the clam.> Also, what type of corals would you recommend keeping with the clam? <This depends greatly on your taste in corals! Anemones are not a good idea. With other corals just be sure to give the clam its space, and that your corals do not shade the clam. Certain corals lend themselves to be kept with clams, such as Acroporas, simply because they have similar needs in tank conditions (high lighting and flow needs). Thank you <Welcome, Scott V.>

Re: Crocea Lighting 1/10/08 My apologies. The question I wanted to ask is, what spectrum bulb will most benefit the clam? <No apologies, it is the nature of computers. As for bulb spectrum for clams a 10K bulb is far and away considered the best choice. The higher Kelvin bulbs do not provide as much 'usable' light for the clam and the lower Kelvin bulbs (6500's) tend to be too yellow for most people's taste. Much info on this is in the FAQ's as well as the link below. Good luck, Scott V.> http://ClamsDirect.com/ Thank you

Derasa Clam Lighting -- 04/10/08 Dear all knowing WWM crew, <<Eric here today'¦ Hardly 'all knowing''¦but I am learning more every day thanks to my association here at WWM! [grin] >> Your website is very helpful, and I have gotten many answers from it before. <<Ah, good>> I am hoping you can help with this question... <<Will try>> My tank is a 50 gallon reef, 48" long 13" wide 20" high. I have a 29 gallon sump/ fuge and an ASM G-1x skimmer. The tank is primarily LPS, and is lit by a 250-watt PFO HQI with a USHIO 20k bulb. Is this enough light for a Derasa clam? <<The short answer is, yes'¦ But even though Tridacna derasa is considered a lesser light-demanding species, it would benefit from some lighting in the 'longer' spectrums not provided by the 20K bulb (i.e. -- a lower a bulb with a lower Kelvin rating), in my opinion>> I had 2 65 watt PC actinics running before, but with the 20k, <<A lot of 'blue'>> I stopped using them. I was thinking of possibly using 50/50s or 10ks instead along with the 250. <<I would rather see this the other way around'¦use 10K for the higher output MH bulb, and supplement with Actinic fluorescent for reasons of personal aesthetics>> Would this be a good light addition, or am I fine without them? <<The clam will probably fine as is>> What is the best K rating for these clams? <<Lamps in the 10K range probably provide the overall 'best' spectrum sampling>> I do have a 14k if that would be better. <<Give it a try and see what the clam thinks>> I appreciate any and all input! Thanks, Jarod <<Happy to share. EricR>>

Lighting for 120 gallon reef with clams 8/15/08 I am in the process of setting up a 120 (4' x 12" x 12"). I would like to keep clams. I have been looking at the Nova Extreme T5 lighting fixture with 8x54 W bulbs. Four of them are 10,000 K daylight bulbs, and the other four SlimPaq 460nm Actinic for a total of 432 W. <A nice fixture.> Will this be sufficient lighting to keep clams, and just about anything else in the line of coral that I may want to keep down the road? <Yes and no. It greatly depends on the individual species of clam/coral you wish to keep and where in your tank. Personally, I would swap out two of the actinics for 10000K bulbs. Having two vs. four actinics will not change your look too much. The nice thing about the fluorescent fixtures, T5 included, is that the placement of the actinics can have a huge impact. Placing the actinic bulbs at the front of the fixture will give the look that most want while allowing you to run the balance in daylight bulbs. Even then it will be a bit weak for a Crocea clam near the bottom, half way up or higher will be fine, where such a clam should be anyhow (on the rockwork). For the end all, be all lighting to keep the critter wherever you want I would think about adding a couple more bulbs.> Thank you for your help. Jeff
<Welcome, Scott V.>

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