When are tridacnids totally photosynthetic?

[Rhinecanthus]

I have heard roughly 2.5-3"

Is that pretty much the accepted size for a clam to be before it doesnt need regular bowl feedings and just good lighting and perhaps occassional tank phyto dosing?

 

[mbbuna]

clams will always filter feed but when they are about 2 1/2 to 3" there mantles are fully developed and can then support them 100% on light alone.

before they are 2 1/2 to 3" there mantles arnt large enough to house the amount of zoox they need to support themselves on light alone, so they need extra feedings from us.