First of all is this a reef tank or a fish only tank?
Second, did you guys let the tank cycle before you threw any fish in?
Third, a good start would be any micro algae like calerpa (sp?). Thats what I use. My 100 gallon tank is connected to a sump, the sump then connects to my refigium which has the calerpa in it for natural filteration. It actually works alot better then the bio-balls and all that other stuff that cost hundreds of dollars.
Wild caught fish are a hit or miss. I would suggest raising the temps to around 67-69F and make sure the fish have plenty of hide spots.
Anyway its really hard to help ya on this with no knowledge of the tank at all. Good luck, and if your really worried about the ammonia levels I would do a 25-30% water change and cut down on feeding. Extra food sitting around will cause amonia spikes. IF you prefer to feed the fish alot, then get some cleanup critters to take care of the extra.