I keep both sun corals and dendros in a 20 gallon tank. I feed them every other day and have never had any issues with ammonia/nitrate/nitrite spikes. I do weekly water changes and keep feeding to a minimum.
Usually feed a combination of plankton, brine shrimp, and mysis shrimp through a turkey baster and use a 20 oz pop bottle with the bottom cut out. Be sure to de burr the pop bottle cut out before use. )
I purchased my sun coral as a resue coral from Saltwater city and it only had 2 heads for 10.00. Now with feedings every other day it has five heads.
My Dendro was around 35.00 at BR for 3 heads and now has six heads.
Yeah great deal for sure. I didn't realize what a great deal I got until I saw dendros at BR after I purchased mine and wow... they are a nice priced coral for sure. *lol* )
Guess when it is time for fragging I'll have to pay it forward. )