problem with return water pressure

[meeka]

sorry, it has been a long road with this pool this year. yes it is a pentair.
the pressure is 0 when the pump is off and runs at about 14-15 when I turn it on, after about a half hour the return water flow decreases but the pressure stays at about 12-13. when it is on recirculate it stays at the 14-15 level.
the pressure gauge is new this year.

[mas985]

Let me make sure I understand the symptoms.

In filter mode, pressure drops from 14-15 PSI down to 12-13 PSI after 30 min and flow rate is reduced. Does this repeat when you turn the pump off then on again? You gave a range of PSI, does this mean the needle is moving or is the pressure between the two marks?

Pressure and flow rate remain the same in recirculate mode. Have you run this for at least 30 min too?

No air in the pump basket?

If the problem was in the filter, pressure would increase with decreasing flow rate. However, since the filter pressure decreases with decreasing flow rate, the problem must be before the filter gauge. But since it does not occur in recirculate, it cannot be anything before the filter.

So assuming the filter gauge is correct, the only thing I can think of is that there is something wrong with the multi-port valve. Perhaps a torn or misaligned spider gasket. When in filter mode, is any water coming out of the backwash line?

[meeka]

thanks for your response. I had pretty much replaced every connection on the system, and since it was working fine on recirculate I determined it had to be something in the filter. Tonight I took the entire sytem apart, took all of the sand out of the filter and cleaned everything. I found some mid size clumps of something ( not sure what- maybe some hair and we have lots of cottonwood here from he trees and who knows what else) and a lot of small pieces of alge ( the water was green when we took the cover off) I repeatedly rinsed the sand until I could get most of the dirty water out. I replaced the sand, reconnected everything and the water flow is stronger than ever and steady. So I think I finally got it! thanks for eveyone's reponses.

[PoolDoc]

Thanks for the follow up!