well it will be going into a 20 gallon, half sump half refunguim, from a 44 gallon corner tank, it will be about 4 feet away from the main tank. It is supposed to be rated at 840gph at 4 foot but....we all know how accurate companies are with there measurements so I figure about 700 to 750 and idk now that I think about it….it is pretty high…do you have any other suggestion on a slower pump that could be regulated maybe down to around 660, I believe that is the rate of the overflow that I have. Thanks guys