What I'm going to tell you is what was told to me, what you do with that is up to you. I ignored it and now I want to follow it. Stick with one tank. It's easier to maintain and you'll spend more time enjoying it rather than dosing, w/c, fixing issues. With that said I have 3 sw and 2 fw. I really want to go with 1 sw and a frag tank plumbed to the DT. The FW are very little maintenance so I'm ok with those, but the dosing schedules on the 3 tanks is hectic. I have to test all the water separately and dose accordingly to each one, not what I want to spend my free time on. I'd rather be figuring out what fish I want to add next, coral placement, powerhead needs, equipment upgrades....that kind of stuff. So I would tell you to hold what you have. BUT it's your setup, get as many as you want.