emily, DO NOT give advice on stuff you dont know. This tank is way to big for snails to make a dent in the problem, besides snails dont eat fish crap.
if its algae and uneated food, get a few Plecos. (unless you already have)
not the best algae eaters but i wouldnt put Goldfish, Ottocinclus, or Chinese Algae Eaters in that tank.
But yeah, youre overstocked