Oh, also, save your old smaller tanks if you have space. They can serve as temporary quarantine tanks when you need them so they don't count as actual fish tanks. That's how fish math works. Ideally you could keep one of your tiny filters in your new big tank. It will add to filtration which is never bad. It will keep a live bacteria colony growing in it. When you need a QT tank, you can just take the small filter off your new 30, use water from your 30 to fill your temp QT tank, and then put your fish in the small tank for a bit. It sounds like you already have everything you need.