More flow than that actually tends to be more bother and expense than it's worth anyway. It is much better for flow in the display to come from powerheads.
No problem it was just suggestion I have mine ran with 1 inch pvc splits to each side then a y coming out locline and 2 thin deflectors to disperse it on both side the diffuser really cuts it down I just had a 9.5 so I built around that but I'm sure you can replace 14 dollar impellar and your pump should be great again I just replace a impellar on a mag 12 it was like new again the magnet had some chips that were making noise marine depot got it for 14.95 free shipping