i was just looking at some units online and noticed that some have a flush valve...i went to see if mine had one...i noticed something weird...the water flow arrow on one of the filters was opposite of the flow direction that i had it ..i had it coming in where it should have been going out and vice versa. my water would literally trickle out from the filter...i posted my concern about this when i bought it...i thought that was the normal flow rate.....i just reversed the 2 lines and this thing is putting out some serious flow now ... now my question is....if all the water was still passing through the filters, just in the wrong direction, do you think it affected the water quality??????? i haven't had any algae problems or anything and i have used it alot!!!!