Hayward DE6020 returning dirty water

[svpool]

We recently had a large algae bloom in our pool. We shocked it and ran the filter for three days straight. The pressure went up normally at first but then stopped increasing after backwash.

We took apart the filter and checked the grids, which are the original ones from the filter install in 2002. They were generally in good shape, but one had a small tear, so we ordered and installed new Unicel grids. We then loaded the filter with cellulose (11 5/8 oz, which is 15 scoops).

Running 12 hours with the new grids, the pressure is still not increasing from 13 psi (our normal pressure after cleaning). Also, when the spa is drained and refilled with filtered water, the water looks dirty.

We took it apart again to look for cracks/leaks. All parts look good, including O-rings. We're going to regrease the return tube (it had grease but we'll put on fresh). We will also now shock the pool again (not done for several days as we waited for the new grids to arrive). When we backwashed, the filter certainly had algae in it, but the return was not noticeably cleaner.

Other suggestions on what might cause the filter to return dirty water and have consistent low pressure with new grids?

 

[OldPoolMan]

Did you check the BW valve? That would account for dirty water returning to the pool Did you get cellulose returning to the pool when you added it to the filter? The only other possibility is that the grids are not installed tightly enough in the filter manifold or the manifold itself is cracked

 

[jtaves85mcss]

Please see diagram in following manual. If the 'return tube' you note is in fact part number 18 - upper elbow it should have an o-ring (part 17) in a slight groove right where the upper manifold slips over it. That has to be in position and lubed.


https://www.hayward-pool.com/pdf/manuals/ProGrid-DExx20.pdf

 

[svpool]

Yes, we did check the BW valve. We didn't see cellulose returning to the pool. We did recheck the grid installation this morning as well carefully go over the manifold. The directions for tightening said to be snug but not overtighten - it seemed to match that description.

Maybe we just need to be patient...

 

[svpool]

Yes, the o-ring is as you have described and is lubed. We have a new O-ring on our shopping list for the next disassembly, even though it appears in good condition.

I was surprised that there wasn't a tighter "sealed" fit where the grids meet the manifold. But it's hard to see exactly how far up they fit, so maybe they do effectively touch and form a leak-proof join.

 

[jtaves85mcss]

I can tell you the first time I took mine apart and replaced the grids it went back together slightly turned/cocked/twisted and would not sit quite level. The grids were not quite seated correctly, and the tubes at the center of each grid were not all the way into the manifold. The fabric around the tubes should basically be crushed down where they meet the manifolds.