1 canister enough ?

Depending on fish load, I might add another AC or canister for that size tank. You want your filtration to turn the tank over at least 5 times a hour at a minimum IMO. This would require that your filters total 750GPH or higher.

You should post this in Gen Freshwater, this forum is for non-fish related topics. Don't worry about it not being seen there, many people check that forum.

Ac, you'll get better replies if you pick a category that interests you.. All of us general chit chat folks just make stuff up =)

btw, I'd say no on that filter being enough... Cichlids are messy and that's a substantial tank... Sounds impressive though, post a pic of your rock work!