You do have enough filtration but mini refug will help you with the nitrate. The fluval won't be of much use in saltwater. I used a 20gallon aqueon for chemi pure elite and purigen. Ofcourse it is not mandatory or anything, just helps
The fluval heater is keeping up nice 77 degrees and holding...and yeah I'm following nitrates and ammonia and nitrites and ph lol every second day