Clams

[mansiz]

Clams can help to keep water quality in good condition? Can it reduce NO3? Can I place it on top of a LR? Or it must be placed on sands? BTW is it compatible with cleaner shrimp or green wrasse? And what will hapen to it if there is lack of calcium? Will it die?

 

[pecan2phat]

Yes, clams can help reduce NO3, but you would need a lot of clams to do this! There was an article on how some aquarium used some giant clams in their fuge to lower NO3 and PO3.
All the clams on the market available to the hobbyist with the exception of the species: Derasa, are rock boring. So yes, they can be placed on top of LR. What you want to do is to let the clam naturally attach to the LR. Depending on your lighting, some will acclimate the clam by first placing them in the sand bed with a small flat piece of LR under the sand for the clam to attach. Then the clam would be gradually moved up. Even the Derasa will attach to LR.
Clams do not like direct water movement, so don't place them in front of your powerhead or return spout, they need high to intense lighting. MH is recommended, but the Deresa & Squasmosa will do Okay under adequate PC lighting, Clams under 2.5" need to be fed, Calcium and Alk needs to be high. Your calcium should be in the range of 400 to 450.
Cleaner shrimps are okay with clams but I do not know about the bird wrasse.