well i used to have 3 red bellies in a 90 gallon. they lived to be 5 years old until a power outage over the weekend
I always used prime during water changes and nothing else. I would do a WC once a week at 50%.
I think that was more than enough for them to show color, but they never had brilliant red bellies or anything.
Since they passed, i recently bought a sanchezi from aquascape and im going to do the same thing. I just hope he shows more color from doing 50% WCs once a week. Maybe ill try housing blackwater if i dont see results.
PS: hes on Shrimp and tilapia. ive tried pellets...doesnt go for them :/