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FAQs about Giant Clam Lighting Troubles/Fixing

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, Lamps/Bulbs, Duration, Quality and Intensity, 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,


Clam & Lighting Hi again and thanks for all the help. I don't think any of the LFS would even come close to the help that you have given me in the last few months. I put my 5" crocea in the QT last night and today instead of only opening a half inch at the most in the main display he/she/it is open half way. YEEHAA!!! I am making sure to check my pH, temperature, S.G. and alkalinity are all close to being the same when I do a 5 gallon water change from the main tank to the sump. I don't have the Fluval 404 on the QT yet and am waiting another few days to make sure it is more seeded before putting it on the QT indefinitely. I have the clam and the rock on the bottom of the 20 gallon QT under the 110 watts total of PC lighting. IYO, do you think I should raise the clam to within a few inches of the PC? <No, I would leave as is.> I feel it would be a good idea and should probably shield the PC from the clam blowing water on the lights as well. <I don't follow the shielding the PC's from the clam blowing water comment. If you move the clam closer to the lights, I would think the likelihood is increased that the clam could hose down your lights.> Will this much light be enough for it considering it was under 400 watt MH's and also receiving light from some 160 watt VHO's on the bottom in my 180 gallon acrylic? <It is heard for me to guess an approximate amount of needed light. You need to determine if 8 watts per gallon under 24" is similar to 5 watts per gallon in 12". The color and behavior of your clam is going to tell you. I would probably leave as is unless I saw a problem as I am very reluctant to move any photosynthetic creature once placed.> More help would be totally appreciated! Thanks, Jeff <You are welcome. -Steven Pro>

Clams light problem Hi there, Your fan from Turkey :-) need your help again. <cheers, my friend from afar> I have 50 gallon setup which I have Hamilton Power Compact 3*55w 10K, 1* 55w true actinic, also NO  2* PowerGlo 30W and a 1* Marine Glo 30W/ Lights are 1" from the surface of the water, it doesn't have plexi or protection from the water.   <all excellent and installed properly> I have got  a clam 2 weeks ago, I believe it is Tridacna crocea Metallic blue. The clam was put in 2 inches below the water.    All seems fine, but I have noticed that the clam mantles started to have flaky burn type markings on them.  All over the mantles.  It looks like skin burns.  Since then I moved the clam down to the sand and I hope it will get better.10" below the water line <hmmm... its OK to put this clam lower, but not for too long (2-4 weeks only). The symptoms do not sound like a burn from bright lights. Excess light would cause bleaching (paling in color) from the zooxanthellae being expelled. The clam would also let go of its foot in such a circumstance and tumble to a lower/darker place. It sounds instead to me like a problem with a predator like a damselfish or dwarf angel picking occasionally at the mantle> I also have a bubble tip anemone in the same aquarium last six month  just 4" below the waterline, it always hide, it is glowing white color.  It feeds well and seemed happy with 3 ocellaris clown.  But it does not grow and the color do worry me. <yes... the white color is a problem for lack of symbiotic algae. If this occurred after you bought the anemone, we may have a light or water quality problem. If the anemone was white when you bough it however, it is unfortunately too common. Feed well (daily ) regardless, while we wait for this specimen to regain color> I douse regularly carbon, so my water is always clear. <very good> >Do you think it is the UV from the lamps ? <doubtful... little from these fluorescent bulbs>   What do you suggest for me to do?   <you can experiment with a thin glass or acrylic lens between the lights and water if you like... but is must be cleaned weekly at least> Murat Ozturan :-) :-) :-) <best regards, Anthony>

Lighting for clams Dear David, Thanks for the instant reply, what a pleasant surprise! <You're welcome my friend in fish!> If I do not want to use metal halides and use VHO instead, what sort of wattages is recommended, <With VHO I would shoot for 300 (maybe slightly) more watts> as I was told that the MH creates a lot of algae. <Nutrients, phosphate and silicate create the algae. Light just helps it proliferate.> My tank is 19" deep, can my corals survive? <With the 4x18 watts that you currently have? No.> They are star polyps, bubble coral, a leather and a sea mat, xenia and a colt coral. <None of them long-term...especially not the bubble.> I have them for 3 months already and they seemed to be happy, they open fully when the lights are out for 14 hours (11 hours with four lamps and 2 hours with 2 lamps, 2start 1 hour earlier and the other 2 ends 1 hour later). The clams I have is already 6 weeks in my tank and so far the colors are still intact. <Remember what I said about things "looking happy?" They're stretching out trying to catch all the light they can. If 75% of your food (photosynthesis) came from the sun, what would happen if you only got 72 watts when you normally lived outside in the ocean getting full sun all day...every day? You would eventually starve. So will they...I'm afraid. Watch the critters carefully.> Thanks again for your advice. <You're more than welcome. Don't just take my advice on this. Research carefully.> Regards, Daniel <Lighting is a complicated issue but IMO this situation is pretty clear cut. David>

Metal Halide, Shallow Tank, and Clams - 06/12/06 Hello, hope ya'll are having a fine morning. <<Mmm, yes...for a Monday>> Just got back from my bachelor party so I can't complain. <<I see>> Anyway, there is a lot of advice out there as far as the appropriate wattage/mounting depth to correlate with certain tank depths, but I can't seem to find any that fit well enough with my situation. <<Much left to personal opinion/subjective interpretation>> Currently I have a 250W double-ended HQI MH lamp with 14k bulb.  My aquarium is a 40g flat-back hex with a depth of about 20" from top to bottom.  After accounting for substrate and unused space, the greatest depth any of my charges can be possibly kept is 16". <<Okay>> My lamp is mounted approximately 8.5" away from the water surface. <<If your corals are acclimated to this lighting then this is fine.  But considering the wattage of the bulb/depth of the tank you could easily move it up several inches...in my opinion>> With the use of a fan heat is kept within sane values (78 degrees). <<Much to be said for evaporative cooling>> I'm worried though that this might be too much light. <<Depends on what you are trying to keep>> My coral charges seem fine and quite happy with the new arrangement. <<Then likely nothing to worry about>> My T. crocea (which I received shortly after) did expel some zooxanthellae right off even though it was placed in the bottom of the tank, <<More likely due to shipping/handling stress, than lighting>> currently it seems fine (mantle spread, not gaping) and I have had it a week now.  My main concern is for my smaller juvenile T. maxima (w/ darker gold coloration). <<Any Tridacnid species under 2" is problematic (seem to be especially susceptible to shipping stress/problems with acclimation)...best to obtain these clams at 3"-4" in size for the best chance at keeping them alive>> Is my concern misplaced, as these are light loving creatures, or should I consider raising the lamp considering the depth of my tank? <<What is the clam telling you?  If it seems happy and healthy then leave as is.  But I also think raising the light a bit won't "hurt" anything if you should so choose>> The T. maxima seems to be happier on the whole since I have started using a sodium nitrate solution.  It concerns me though that no matter how much I add I still seem to have 0 nitrates. <<Likely used/removed very quickly...be sure to make increases in small increments...and keep a sharp eye out for the start/increased growth of nuisance algae>> Could this solution be taken out by a skimmer or PolyBioMarine's Poly-Filter? <<Yes>> It doesn't seem likely, being a salt, but my knowledge in that area is pretty limited. I'll appreciate any knowledge you wish to pass my way.  If perhaps I have missed this information in your faq, I apologize. <<No worries mate>> Thanks for your help! James Tanis <<Cheers, Eric Russell>>

Unhappy Tridacna squamosa...Too Much Light Too Fast? -- 05/09/07 Hello, <<Howdy>> I purchased a 5 year old Squamosa (about 6-inches) approx 7 days ago.  I  did a two-hour drip and it acclimated very well for the first day.  The  second & third day it didn't want to open much, so on the fourth day I gently nestled a rock under it so it could foot hold. Almost immediately it opened up beautifully for about two days.  Now yesterday and today it is gaping on and off and the interior of the clam seems sunken in. <<Mmm...>> It is open and the mantel is out and the clam is very  responsive. <<A good sign>> Also the color looks good.  Is it doomed or can I do anything? <<There is usually little we as hobbyists can do for these creatures once they show signs of decline, but if the decline is attributable to an environmental situation that can be identified and corrected  the clam may pull through if not too damaged/too far gone>> It was raised under VHO lights and is now is in a 75 gallon with 2 250-watt metal halides. <Ah!  A definite clue...  If the clam was not acclimated to the more intense lighting it is likely suffering from photo-shock.  You can try shading the clam a bit with layers of fiberglass window screen or the like (have a read here and beyond for more info: http://www.wetwebmedia.com/acclimcoralslight.htm), removing a layer every couple days to allow the clam to become accustomed to the new lighting...though since it has been more than a week since the clam was placed under the halides, this strategy may now be a moot point>> Ammonia 0 Nitrite 0 Nitrate <5  Phosphates 0 PH 8.4 SG 1.024.  I have a lot of sensitive corals like Alveopora and  a Crocea and Maxima and they are well so I don't believe it is the water. <<Then is likely the lighting>> Its bottom dwelling neighbors are a 3 plate Fungia  about 3-5 inches away and the other side a Lobo about 4 inches away.   Any help would be great. <<Do also have a read of this article by Barry Neigut of Clams Direct on selection and placement of Tridacnid clams ( http://www.wetwebmedia.com/ca/cav1i3/Clam_care/Clam_care.htm ).  Regards, EricR>>

Loss of powder brown tang 12/26/07 Hello, First off I want to thank you for putting together such an informative site. I have a 125 gallon tank with an attached 30 gallon refugium and a 20 gallon sump. I have about 175 lbs of LR throughout. DSBs are utilized in the display tank and refugium. Specific gravity kept at 1.024 <I would raise a bit.> and temperature at 75 degrees. Inhabitants included: 1 Powder Brown Tang, 1 Tiger Wardii Goby, 1 Orange Spotted Goby, 1 Crocea Clam, 1 Skunk Cleaner Shrimp, & 1 Peppermint Shrimp. My heater stopped operating yesterday and being that it was Christmas, I was not able to purchase another. <Yikes, a back up unit next time?> It was cold last night for Arizona standards and the temperature in the tank must have dropped into the sixties. I woke this morning and found the tang dead. I checked the water parameters and everything checked out fine. Do you think it was the drop in temp that killed him? <Sounds likely.> I added the clam a few days ago and it has periodically excreted something from its spout, but I was leaning more towards the temp drop. Also I was wondering, I have two 6 ft blue actinic bulbs running off an Ice Cap 660 ballast. Do you think this will be sufficient lighting for a Crocea clam if I place it near the top of the tank? <No, not enough light and wrong spectrum.> Would it make a difference if I replaced one of the bulbs with a 50/50 daylight bulb? <Very little, you simply will need more light for the clam. Read more on their needs, start here and related FAQ's http://wetwebmedia.com/ca/cav1i3/Clam_care/Clam_care.htm Thank you for your time <Welcome, good luck, Scott V.>

Re: Loss of Powder Brown Tang 12/27/07 Thank you for your quick response. I went out and bought a digital heater and a back up. <Good.> As for my question concerning lighting for the Crocea clam, would it be advisable to run metal halide lamps using the Ice Cap 660 ballast? <Halides would be good, but not on that ballast. You will need the ballast rated for the wattage and type, single or double (HQI) ended, you intend to run. Take a look at different Etailers and the ballasts sold for particular types of bulbs. Hope this helps, Scott V.>

Tridacna maxima, light loving? 06/24/2008 Hello Crew, <<Good morning, Andrew today>> I have a question about my 2 maxima clams. <<Sounds good>> They are placed about six inches from the top of the aquarium, as they are bright blue. I read the brighter blue they were the more light they required. <<Well, the blue clams in general need more light, over and above the clams with a brown mantle. Blue mantle clams are mainly found in shallow water and the mantle acts as a kind of light filter for the zooxanthellae>> They look good until after the lights have been on for approximately 1 hour then they begin to gape slightly. My theory was a PH drop, however PH holds and dKH is 10. <<Param.s sound fine>> We have had them for about 6 weeks. They were bought from a LFS after holding them for us for 2 weeks. They had been kept under T5's at the store. They were transported home and acclimated over the course of 1.5 hours or so by slowly adding our water to the bag. We did not quarantine them due to PC lighting in the QT tank. I have ordered Knop's book on giant clams, however I thought you may be able to shed some light until then. I read through Calfo's invertebrate book and on the internet for someone having the same problem. <<Gaping is usually a sign that the clam is trying to tell you that something is not right, sometimes the gaping of a clam can mean that its basically on its last legs. How many watts of lighting do you have on the tank? as you do not state this in the email>> About our tank: Started 12/07 ~6 months old 125g tank, venturi skimmer, 5 powerheads, live rock in tank and sump, ChemiPure, 4 T5's 2 actinic 2 full spectrum, chiller SG 1.024-1.025 Ammonia 0, Nitrite 0, Phosphate 0, PH 8.2-8.3 We are in the process of setting up a refugium in the sump. 10% water changes weekly. Inhabitants: 1 six line wrasse 1 six spot sleeper goby 2 Perculas 1 blue tang 1 neon goby 6 cleaner shrimp 6 turbo snails 6 small hermit crabs 1 Rose BTA 1 finger leather coral 1 small colony of star polyps <<Don't see any real problems with your stock, may have prob.s caused by the cleaner wrasse. For me, I would put this down to a lighting issue. Sometimes, there is not a great lot we can do, but keep a close eye on the coral, and keep pristine water parameters. As another thought, if there are any corals, anemone's near to it, you should consider moving to save the clam being aggravated by neighbours. Please do read more here. http://www.wetwebmedia.com/ca/cav1i3/Clam_care/Clam_care.htm >> Thank you for your time. Your web site has prevented many mistakes. Jo Anne <<Hope the above helps, thanks for the questions. A Nixon>>

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