Back in the day when I had a bigger tank I had a fuge/sump (lots of macro-algae) on it when it was just a fish only tank (had some live rock) and the water quality was great. I had a bamboo cat shark, a lion fish, and a puffer. the water quality was great and with a fish only tank if I am not mistaken you can use alot more carbon (all the time) due to not having to worry about leaching good things out of the water for the corals. I had macro algae and carbon as well as filter floss running (changed it every other day) and the water was quality was nice