Prism Pro Bubbles

[Delphinus]

I take it you don't have a sump? That will limit the options a little unfortunately because you don't want it to look too ugly.

Emptying the outflow into a chamber that can only overflow into the tank might help, or draining through a sponge of some kind (but you will have to clean the sponge regularly) or maybe just some kind of plastic to break up the flow.

Not sure offhand what else to suggest but I'm sure someone will have a clever idea for you.