I've been helping a friend set up a 55 gallon and so far all is going good but he is having an issue with green algea. The lights are on a timer set for about 8 hours a day. The main question is what snail would be best for a tank this size? The another question is should I worry about the angel in the tank attacking it? Also he plans to get a clown pleco and would a snail be competition for food? I don't plan for the pleco to live off algae but I believe they both feed on it. Additionally, when the fund are available we plan to add plants to help use up extra nutrients.