after backwash, strong suction, then fades to a trickle after 5-10 mins

May 17, 2016
1
flower mound, tx
I just replaced my DE filter grids that were cracked with these from ebay: Pleatco Swimming Pool 48 Sq ft de Filter Grid Set for Hayward Pentair Filters | eBay

Since then, whenever I initially turn on the pump, water is flowing nice and strong through the system, the kreepy krauly is flying around the pool, the pressure gauge reads 25. Everything seems great. But slowly after about 5-10 mins, kreepy krauly slows to a stop, water is barely flowing through the system, hardly any suction in the skimmers, water barely trickling out of the returns, and the pressure reads as high as 45. It must be the new filter grids right? I'm guessing maybe the construction of the weave may be too tight, preventing water from flowing through it easily and therefore the high (45) pressure? I've worked on every aspect of this pool for over a decade so I get how it works, but in this case I am at a loss.
 
It must be the new filter grids right?
No. I do not think you have filtration issues but rather chemistry issues.

As a result you are sucking algae (even though you may not see it) into your filter and clogging it up.

My guess is you need to SLAM your Pool but can you post a set of current test numbers first?
 
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