I am looking at something for addiitonal water movement in my 75 gallon tank. I have an XP3 going. I think the water doesn't circulate to the opposite end of the tank as much as I'd like to see and I've been looking at options. This aquaball interests me. It looks as if it could be used as a powerhead and also as a filter, and has the capability to rotate the head to direct waterflow where you want.
Has anyone used this product? How big of one should I get to use in addition to my XP3? My other choice was a fluval in tank filter, but this looks to be a flexiable piece of equipment with other uses if I change configuration of my tank in the future.

I suggest that you find a 100-200 gph submersible pump (at that small size they aren't usually called powerheads), make a spraybar to fit the outlet pipe, with the bar being almost as long as the tank, then set that at the back and at the bottom of the tank, with the spray holes directed towards the front of the tank. Then just poke the CO2 line into the inlet grid for the pump so the bubbles get chopped up by the pump rotor and sprayed all over the tank. It adds a lot of current, and quickly fills the tank with CO2 mist. That's what I use, and I'm very pleased with it. I used transparent acrylic pipe - 5/8 OD - 1/2 ID - from Tap Plastics, where I also picked up a little 1/2" disk of acrylic and some cement to stick it in the pipe to close it. Very cheap and effective. I did have to take a small file and file off a bit of the barbs on the pump outlet pipe to make it fit easy into the tube.