I have a Big Blue CLEAR sump water filter 4.5 X 20 what O-Ring. I have been told round and also been told square cut .... I'm about to change the filter need to know this is the first time and I want to make sure that the o ring is correct ... too long of a drive to go back and forth.
The sites I go to say O-ring part # OR-100 But NOT FOR CLEAR HOUSING !!!