Freshwater clams and algae effectiveness??

[krissyfish20]

I'm just wondering if anyone has had any good experience with freshwater clams/mussels and their ability to clear algae. I work at the uni, and some of our big zooplankton(daphnia to be exact) tanks are so overrun with algae (it all started during the extreme heat at the beginning of the summer and with us not innoculating with daphnia right away) that now we cannot culture any of the zooplankton. we have been filtering out half the water in the tanks and then back in to clear some of the algae (they just have to be a little less green, not completely clear), but the filter is 100bucks a week to rent and the filter bags are 26 bucks each and we need 28 filters. I thought that clams might be effecient enough if we put a number of them in each tanks and left them. does anyone know how efficient they are?? I've heard they're good!! Thanks.