Thanks. I will test for calcium hardness - but typically mine is low not hard; but I will check.

There is a pressure gauge on the filter. I suspect it doesn't work as it never really changes, LOL. I've never bothered changing it. I've backwashed recently after vacuuming, basically after return flow gets low. When I backwash, there is dirty water that appears in the glass, then it clears - like normal. During a regular season I do not usually back wash very often. It's usually only during opening that I have to backwash more than normal.

Nothing seen coming from return into the pool. I use liquid chlorine - 12%. I usually just follow BBB method & my pool is normally crystal clear. I'm not one for adding a lot of stuff to it - except this time when I tried the clarifier & floc - will hold off on doing any more of that though.

Let's see....pump is I think 1.5 hp Hayward & filter size...not sure...will have to go back out & check. Not thrilled with the idea of messing with the impeller or filter as I have never had a problem before.