what do you have in regards to filtration on this setup, if its a canister filter you could go to wal-mart and get one of those rena dual HOB filters as a second filter, i think they cost around 30 bucks or so, they work fine for me on my 55gal or a large hydor sponge filter tucked away in the setup, didnt you say you were getting 5 shellies if so if you add the shells you have that will be like 5 shells per fish ratio with the exception of one fish only having 4 shells really this is a issue you will need to come to terms on, i over do it on shells, my opinion is the more the better, but you can get away with 2 shells per fish, what you dont want to create is turmoil within the shell community hence adding extra is better in my opinion..