Clogged filters in 55 gallon?

dont take all the media out, take one pad out and give it a good clean, its what i do with most of my tanks, i have two or three other layers, and i wash one or two out properly,then leave the others be, never had a problem. check the impeller, if a vane has broken, or it is clogged, that will cause a drop in flow rate. the other thing is to try to get as much air as you can out when you prime it.