Hello everyone, this is the updated version of my previous “Lighting Requirements for Tridacnids” thread. I hope this one will answer your questions in regards to providing your clam with the best lighting conditions possible. Most of the information here is based on personal experience and experiences shared by other fellow clam lovers. Supplemental information is credited to James Fatherree and his book, Giant Clams in the Sea and the Aquarium, and many thanks to Chris for his never ending help. Please read the entire post as the information is designed to support each other. (especially the Tridacna Crocea section)

Please remember: Squamosas, Deresas and Gigas WILL outgrow your tank fairly quickly!


Tridacnid Lighting Requirements:

Tridacna Crocea



These clams require the most light of the Tridacna family. They occur in the wild mostly in very clear waters less than 15 feet in depth. (6 meters according to J.F.) The minimum recommended lighting requirement for a healthy Crocea is under a 150 watt metal halide of a reliable 14k bulb at a maximum depth of 20 inches, preferably less. To be on the safer side, a 10k bulb is recommended, and is closer to the "true" color of natural sunlight. I have seen some Croceas under 70 watts of halide, but these are normally placed high up in the tank. 70 watt bulbs are also considered by some as the least developed bulb, therefore being more inefficient in terms of their output compared to their 150 watt counter parts. 150 watts of (14k) metal halides would be the minimum “safe” amount of lighting. They will do even better under a 250 watt or 400 watt metal halide. If you are using 250 watts and above, you can place the Crocea even deeper in your tank, or even use 20k bulbs. If using T-5s, make sure the bulbs have individual parabolic reflectors on them, and the clam is placed at the upper half of your tank to be “safe”. Power Compacts will in a lot of cases NOT be adequate for Croceas.

In the case of T-5 lighting, remember only the 10k bulbs produce enough photo energy for PAR on clams, and the actinics produce little to no PAR depending on color temperature. It is also noted that the longer the bulbs are, the more penetrating power they carry. Thus a Crocea should be fine in a 20 inch depth under a 36 inch fixture. Having a Crocea in a 20 inch depth under a 24 inch fixture raises doubts, as most 24 inch fixtures only have 4 T-5 bulbs under them, with 2 of them usually carrying heavy actinics or some shade of high color temperature bulbs. In this case a retrofit is recommended to be able to cram in more lower temperature bulbs.

Tridacna Maxima



These clams require almost as much light as Croceas if not as much. In the wild they have a maximum depth of occurrence slightly deeper than Croceas, but are again mostly found in very clean and shallow waters. The best bet is to place them in the same lighting conditions as you would light a Crocea. The “safe” amount of lighting would be under a 100 watt metal halide if they existed, so I’m going to say 150 watt 14k metal halide under 20 inches or less as well.

Tridacna Squamosa



These clams are much more forgiving in terms of light than the upper two tridacna species. Assuming they are not placed in a nano due to the size they can reach, they will be happy under metal halides of some sort, but will suffice with vhos, or even power compact lighting. There is no exact number for the wattage of the bulbs, but the “safe” amount of lighting would be anything above 100 watts of compact fluorescents in depths of less than 20 inches provided they are directly under the bulbs. T-5s are recommended over your regular power compact lighting, and a Squamosa will soak up Metal Halide lighting very happily.

Tridacna Gigas



Can suffice with even less amount of light compared to the Squamosa. They can thrive under most pc /vho combination, but again will be happier with lighting closer to that of its natural environment. Gigas can be found at depths up to 20 meters (J.F.) but some of the most successful aquarists have them under some type of metal halide lighting system and have recorded tremendous growth.

Tridacna Deresa



These clams are probably the most forgiving in terms of light than the rest of the mentioned clams. Their maximum depth of occurrence is about 25 meters (J.F.), but like the Gigas, they will be much happier with the lighting requirement given to Squamosas.

Exceptions to the Rule

Many people claim that Croceas and Maximas can survive under power compact lighting. These cases are far and few between, but there are certain individuals that are able to tolerate lower lightings, at which most of their counterparts would not be able to survive. Nevertheless, you should not take the risk and hope to get lucky, it is better to be prepared to give them what they will surely thrive in. It is always good to provide at least enough light of the given species to thrive in, and NOT the bare minimum you think you can get by with. Plus, it is the least we can do for our animal, as well as our responsibility as hobbyist.

Light Acclimation

There is no artificial lighting stronger than the great ball of fire in our sky, so all clams can adjust to your lighting provided they are given proper acclimation. This is especially important to prevent light shock, and gives time for the natural population of the clam’s zooxanthellae to adapt to their new habitat and photo conditions. Acclimation can easily be done using egg crate screening, or other materials that cut/diffuse lighting intensity. Remember, switching from fluorescents to metal halides is a big change, and so is switching from 150 watts to 250 watts.

Bulb Life

Fluorescent light bulbs need to be changed about every 10 months as they lose their intensity from old age. For metal halides, people have reported that 20ks lose their intensity at 6 months, 14ks around 8-10 months, and 10ks almost one year. I have not seen solid evidence in regards to this matter, but personally change my 14ks every 10 months.

I do not know the origin of the pictures as they were saved in my computer so I cannot credit them appropriately. The sole purpose of this thread is for the benefit of everyone, so please understand I hope this thread has been helpful to all of you.

Tks EZ...nice read

Izzue

Good readings Jin! My crocea is doing just fine under my 96W T5HOs. Granted I keep the clam in the upper half of the tank, and added individual reflectors to my daylight bulbs, so that helps out a bit. What I have noticed is that for my individual, it's really on the edge of lighting requirement in my tank. I say this because when salt residue starts accumulating on the splash guard of my light fixture, my clam tends to open up only slightly or maybe not even at all. A quick wipe down of the guard and the clam is happy again and fully opens. But I think it's adjusting well having gone from the 150w MH in your tank, to my 96w T5HO. For referance to others, my fixture is "24 and my tank depth total is "18. It's recommended that if you use T5 lighting for clams or even SPS, your bulbs should be at least as long as the tank depth or more preferably longer than the tank depth.

So pretty...

thanks for the info EZ's

Just wondering if there is any type of clam that will be able to survive under the stock lights of a oceanic 29gal biocube?

How did you determine this? What if I have 4-75w vho bulbs 2 inches above the tank? What if I have 2 40w NO fluorescent bulbs 3 inches above the clam?

Intensity (PAR in consideration of height) is more important than type of lighting.



Source? I don't know that I'd agree with either statement.



hmm...



hmm...



You seem to have a bias for MH



cool



What about other types of bulbs.

If you didn't notice I'm trying to encourage you to think outside of the metal halide box.

Why not tell people how they can do other types of lighting correctly rather than just push them towards thinking metal halide is the only way?

i have little experience with keeping clams under fluorescent lighting.
i am sure they can be kept with a good combination of VHO, PC, or T5s without doubt. i am simply sharing the knowledge i have accumulated so far with others, and my bias towards Metal Halides is mainly due to the tremendous success of other hobbyist keeping them as well as myself. I have seen clams under T-5s transferred to Metal Halides and the coloration on the mantle compared to the previous lighting was like light and day. Again i am not saying other lighting options aren't viable, but Metal Halide is simply the easiest and most surefire way of keeping a happy clam.

thanks eeeeze for sharing your extensive research and personal experience. that's a great start for a discussion on clams.

lgreen, if you've got something specific to add in favor of alternative lighting for clams (other than MH), please do share.

i feel like cyclop eeeeeze

I second that. I want to hear what specific knowledge/information/experience you have in keeping clams in lighting other than MH. As I'm sure others would like to hear as well.


EZ, good read and I would definitely ask for your opinion if I ever decide to get a clam. I've seen your specimens in person and they are beautiful, so I'm sure you are doing something right.


-Iz

just wondering, did those croceas grow on each other? thats an awesome pic!

What type of clam(s) can I keep in my BC 14 with 72 watts of pc lighting?

A Cleaner clam! Just kidding. You should be able to keep a Crocea Clam until it reaches 3" and higher as it will require photosynthesis at that point for food rather then via feeding. Once it reaches 3" or bigger I would recommend you moving to MH. I have one in my BC14 with just 48 watts of PC lighting and it's beautiful and happy........for now at 2". It eats well and color is still nice. Personally I think once it gets larger than 3" it shouldn't be in a BC14 anyway. One more thing to consider is that your tank should be mature as I've tried to move my Clam to my BC29 with a Sunpod 150W and it didn't appear as happy in that water. Same temp and salinity but my BC14 has been running longer with more LS and LR compare to my BC29 which uses more Base rocks with regular sand. So now I moved my Crocea back to my BC14. I just ordered a Sunpod for my BC14 as well since I didn't want to take any chances but my LFS swear that he has a lot of friends who have successfully kept these larger Crocea clam for years starting at the same size as mine. He even show me pictures. I believe him but I was itching for a Sunpod so I bought it anyway. The only thing that I like about the close top is that I never needed to top off before a water change. But the MH SHIMMER effect made me forget about any hassle. I think at 72 Watts near the top, you should have a very good chance man. Try it out and let us know.

Shimmer on...........

I disagree coral addict. Clams are able to create all their energy needs right from the beginning. The whole saying that a clam under 3 inches needs to be fed is a myth. within a month of the larval stage their mantles are fully developed and full of zoox, and can sustain them with intense lighting. heres a study where larval clams were kept in micro filtered water and not allowed to receive any particulate and they did just fine on light alone.

http://links.jstor.org/sici?sici=00...B2-N&size=LARGE

I personally do not think stock pc lighting will be enough for a crocea, but there are always exceptions to the rule. it is still best to provide them with light you are sure they will thrive in, instead of skimping by and wishing for the best. hope that helps

Great, informative thread!

I am interested in adding a crocea to my tank. In your opinion/experience, how long should the tank be established (ie stable parameters) before I add it?

It is a 20 gallon with 150 watt MH.

I would recommend your tank be at least a few months old with stabilized parameters before adding your first clam most people say 6 months to a year. with some care, you can get away with less.

2 weeks worked for me. Ok, so technically it wasn't 2 weeks, lol!

Great info. Those maximas are so awesome, the most colorful if seen.

I wish i had a clam

Coral Addict: thanks for the info
Ez: I upgraded the lighting from 48- 72 watts- what can I keep with that? I can put the clam within 3-4" of the light... what do you think?

i disagreed with coral addicts info above: "You should be able to keep a Crocea Clam until it reaches 3" and higher as it will require photosynthesis at that point for food rather then via feeding."

i still think 72 watts is a little iffy if you want me to be absolutely honest

Have you read anything about Dr. Shimek changing his stance on the need to feed little clams due to thin mantles? I know Fatherree disputes the whole mantle-thickness argument quite fiercely in his book (which seems to agree with what Sprung and Delbeek say in The Reef Aquarium) but I would be interested in if there's been any retraction or modification of his view.

Darn, and I thought 72 watts was enough

whats the flow requirement for a clam?? do they like alot, medium, or little flow???

i haven't read shimek's article sorry, but i've been told that James F. has reviewed all the limited information on Tridacnids and has come to his own conclusions. there is no doubt that almost EVERY creature found in tropical reefs benefit from plankton in some way, it is simply how the ecosystem is structured due to the water column, and I will definitely say clams will do better with supplemental feeding, but it is not necessary.

72 watts is very very low for a crocea or a maxima sorry!

flow requirements: clams are found where hard corals, soft corals are found, and can tolerate quite a bit of flow. there are no requirements, but i believe that a strong, indirect turbulent whorling type flow is always good. (which is pretty much almost impossible to recreate in nanos)

Oh well. I'm pretty sure Shimek is the one that started the mantle thickness nonsense in the first place when he wrote it in his marine invert book, which was why I was curious if there was something I'd missed from him.

My 12g nanocube has been established for a few months and I just finished a 70w MH retro using a 14K Current bulb. My LFS has several small clams of which species I'm not sure (I'll have to check). The few corals that I recently purchased are thriving and look better than they did in the store. Would you think my tank meets the requirement for a Crocea or Maxima?

okay guys... noobish question- read the thread but still wanted a more detailed answer, esp. if you're keeping a clam in a 12g. i have a 12g nano cube with stock lights and my LFS has some super cute 1-2" clams in their tank... croaceas i think... what sort of upgrade would i need to make if any to get one of these bad boys? is the lighting in the dx models sufficient enough yet, or do i need something else? thanks!

Good luck, I have 70w MH and no one will answer me either.

that's cause your face is duct taped

maybe we should ask something that will get us flamed and then ask the real question

I kept a 2 inch crocea in my 10G for a few months without any problems directly under 70W 10K MH. It did not lose color or gape, and had no signs of stress. It was about 6 inches from the bulb, 4 of them being water.

Can I put a crocea clam, a yellow tang and a moorish idol in my 12g nanocube with 70w of MH?

IMO pc lighting is not enough for a clam. 70w halide, sure why not

Honestly to be safe I'd say you'd want at least a 70w MH. Some people have integrated one into their hoods. I've heard of people try to keep one under stock cube lighting and it died on them within 2 weeks unfortunately.

Nanoty, if you have a 70w in a 12g cube (or even 24g cube) you should be ok. if it's a 24g, I'd place it higher to the light though to be on the safe side...

so is there just a bulb change i can do or does this require a retrofit?

Retrofit. Actually, Nanocustoms ( or something like that, I don't really know all-in-one tanks that well) sells modded NCs, so I think it could be done pretty easily.

Try it first and tell us. Looks like you have extensive experience but it's mostly wiht MH. Most ppl on this site just report what they hear thru the grapevines. I also read plenty of stories about ppl having CLAMs under PC lighting for 2 or more years. Realistically in the Nano space, I think we would all outgrow our environment in 1-2 years. So I say it's doable and my LFS "City Pets" in houston have many reference customers that has it under PC lighting for a while. So if you don't have the $$ for MH but really have to have a CLAM for some reason, look up other ppl's success story and compare their PC setup to yours. Obviously the more light the higher the chance of success but the water parameters are equally important as I mentioned my CLAM didn't like the 150W BC 29 tank as much as my 48Watt BC14 setup bc the smaller tank was more matured. But if you really want it to thrive and look it's best, MH is the only way to go. I did noticed that the CLAM's color came out much more under MH after I upgrade to a 70W Sunpod for the BC14.

Don't clams like a little bit of nitrates or soemthing like that?

yea clams like trates, and a hell of a lot of calc! my little 3" crocea sucks down at least 5-10 ppm a day! and concerning the 12g with a 1", on relatively powerful pcs it can be done, as if you feed the clam most of the nourishment is being provided there, since the clam hasn't developed the full potential of zooxanthellae. But once it has, u better have good lighting cuz it will get its energy only from the lights. but a 1"-2" clam could, key word could, do alright under pcs. but anything larger and u need at least mh, or t5. hth

Are you talking about the metal halide? Check out my tank thread (sig) as well as Qwank's in the members tank forum. We both just did MH retros on 12g nanocubes. I added mine up and it was just a little over $100 all together. I am going to look at some small clams this weekend. I don't know if I want to put one in my tank yet (it's only about 2 months old) but if I find a really good deal I might give it a shot.

It's a retrofit. Nanotuners makes NanoCube PC bulb retrofit additions, I'm not sure of anyone (other than a homemade custom job) that makes an actual cube specific MH light retrofit into the hood. I know of people that did this with their Aquapods, but I don't recall anyone that did one into a NanoCube. I forget which tanke everyone has these days.

So... I can safely deduct that clams are like high lighting chaeto?

clams need nitrates and phosphates, but this doesn't mean they should be detectable in the water column. in a healthy system, as soon as ammonia, nitrates or phosphates are created, they are used right away by marine organisms, such as clams.
i guess what i'm saying is don't go out of your way dumping nutrients in your tank. if you have fish, and you feed your fish, you'll be fine.

So then is say like PhosGuard not good in a tank with clams?? =/

phosguard is rumored to leach back phosphates into the tank as it is aluminum based.
granular ferric oxide phosphate removers boost the iron levels in the tank, which may or may not be the cause of pinched mantle in clams.

Yeah, just my luck... Well they claim it doesn't leach back, but of course they can claim anything they want to. I've had the sack of it in my tank since Jan, so I'm sure it's time to toss it out. Same with the Purigen I have in there too. But running my fuge should depleat excess phosphates anyways. So wait, if nitrates and phosphate is needed for clams, does a fuge go against having one then since chaeto is known to help consume/filter out both of those??

Would Phos-Ban be in the same boat as PhosGuard?

phosban is a gfo based media. it will remove phosphates more efficiently in your system, but the increase in iron MIGHT cause pinched mantle for your Crocea.
a fuge is always a good idea. as long as you have fish and you feed them, i wouldn't worry about your clam not getting enough nutrients.

i have heard good things about purigen, why not use it?

Purigen I DO use, along with PhosGuard. I also have Chemi-Pure that I have yet to use... I should test my phosphates again though to see if I still need to use PhosGuard or not anymore...

i think i'm getting a sunpod this weekend...

then i can get a clam for sure, eh?

Yup, you should be able to after you get it. I'm jealous, I need MH lighting lol!