I've just been mucking around with my filter in my tank and taken the long tube with the holes off so the water just comes straight out. It creates pretty fast moving water in one half of my 3 ft tank.
I'm just checking this is okay with my Red Rainbows and my one Neon Rainbow?
The corydoras and bristlenoses are at the bottom so they don't really care.
I'll add a picture so that you get what I mean