I set up my Eshopps PF-800 and wondered why the flow isn't as fast as they say. It calls for 800GPH, but I don't think it does. The water level is a few inches up above my 1" PVC piping. I haven't done any mods to it, other than tubing to stop the noise. I have raised and lowered the overflow box, and even if the box is totally submerged it only sucks so much. I have tuned down my Mag 7 flow so I have just been going with what I've got. Any suggestions?