I have a couple of the Pentex cascade canister filters sizes 700 and1200. I just purchased a 500 thinking that the tube sizes would be the same. The inside dimensions of the of the two bigger ones is fiveeights of an inch. However the 500 is only half an inch. Has anybody ever tried using an adapter on their filters to go from one size to another? My only concern is on the dirty water side would the inside dimension get clogged up going from 5/8 down to the half into the return valve?