I do 20% weekly water changes and it keeps my levels near identical on both tanks. I use skimmer only, no filter media or pads. Also I only feed nls pellets small amounts 2x daily
red sea 350: powder blue tang, 10 chromis, royal gramma, mandarin goby, clown
red sea 750: 1 angel, 1 butterfly, 5 tangs, 5 wrasse, 2 clowns
Nitrates : 5 salifert
Phos: .05-.1 hanna