Interested to know this too. Keep in mind though, clams can have special requirements of their own.... Pests can bother them and some fish may too.

There is a thread on this topic somewhere in the last 2 weeks, have a look and see if you can find it. Basically clams don't work unless you have a ton of them..

Clams will lower the nitrates but you do need a lot of them.

Google "Reef Videos and Marte Meneses". Marte had 55 in his tank but also look at his fish load!!!

Cheers,
Tim