Large clam keepers!
 

Just got myself a 5-6 inch maxima clam.
So far I've only had small ones around 3-4, longest one living a few years.
Do the larger ones require more feeding or anything? Light isn't an issue they're under 2x250 watt halides.

clams are filter feeders I have a 10-12" squamosa, 8-10 squamosa and I dont feed them.

I have 2 decent size clams and have never fed them anything. Make sure to watch your KH and calcium levels to see how much they use and they can be pigs for chemicals.