I'm cycling a 180 gallon tank right now and i'm about a week away from intrducing the Piranha's to the tank. Would you guys suggest putting in a powerhead and if so, what kind? My filtration is a wet/dry sump system with a pump that is pushing about 900gph? Do you also think that is enough? Let me know, thanks. 8 Piranha's will be housed in this 180g.