I have used eheim compact pumps , but mine are only the 300. They work great for what I am using them for, One runs my dual media reactor, and the other one will be used for my ATO when I get it hooked up. The +3000 has a flow rate of 792 gph and a max head of 2.3 meters, which is about 7 ft. Im guessing with the head loss its not going to be pushing much water if you want to use it as a return pump. I couldnt find a chart that shows the calculations for the head loss. I would look for that and see how it will fit your needs. It looks to be a great space saver, but I would spend a few bucks more and go with a proven thing and get a 1260 or 1262