I have a 5 gallon shrimp tank and a 10 gallon with a betta and some pygmy cories. They both have HOB filters and I'm considering switching to sponge. The flow is a bit much for my betta, even though there's lots of places for him to go out of the flow, I don't love that there's a part of the tank that he doesn't like. My shrimp tank filter works well but rattles and bugs me (i have a sponge over the intake). So for switching, is my best bet to set up the new filter and run both for a while? How long should I leave both in for? Any other words of wisdom?