problem with return water pressure

[meeka]

We just opened our 28'above ground pool, all connections are tight and the pressure gauge(brand new)is working properly. After about a half hour we loose the pressure of the water returning to the pool. The pressure gauge does not change. I have checked everything and cannot figure out how to correct this probelm. I have removed the filer head to check for and debris, and there was nothing there. any ideas?

[Watermom]

What kind of filter do you have?

[PoolDoc]

After about a half hour we loose the pressure of the water returning to the pool. The pressure gauge does not change.

1. Make sure your pressure gauge is not broken: it should be near 0 when the pump is off, and should read least than 20 psi when the pump is on.

2. Two common causes of loss of flow are (a) filter plugging with algae (does your pool look swampy?) OR (b) a suction leak causing loss of prime (is your pump above pool water level?)

[meeka]

it is a pentax filter, when I run it on recirculate I do not loose pressure, I have changed and or tightened every connection, The only other thing I can think of is that there is something ( debirs) in the sand that is blocking.

[PoolDoc]

it is a pentax filter

Pentax makes cameras; Pentair makes pool stuff, including filters. I'm guessing, you have a Pentair.

=> What does the pressure gauge show when the pump is off? What does it show when you have the valve on Recirculate? What does it show when you first put it on filter? What does it show, when you lose flow to the pool?

[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?