Low flow in Filter and Recirculate mode

[monzeez]

I have been dealing with this issue all season.
In both recirculate and filter, the flow in and out of the pool is lower than it should be. Low enough that one of the skimmer weirs will not push down all the way. Also slowly but surely small bubbles form in the pump basket, until it is a large air pocket. In waste or backwash, there is no issue. The flow is full and strong. Often to fully prime the pump I have to start in waste and then switch to filter.

I have done the following

• changed drain plugs on pump
• changed strainer gasket
• changed pump housing gasket
• checked impeller for debris
• blew all the lines to account for any debris in return
• changed O-rings on Jandy valves
• Checked heater for proper flow (by-pass valve was replaced)

I am usually pretty good with the pool, rarely calling a professional service company - at this point I'm at the end of my knowledge. The only thing I haven't done is to start digging.

Thanks, monzeez

20,000 gallon concrete in-ground pool with vinyl coating (aka, aqua bright)
Hayward super pump 1.5 hp.
Hayward 40sq ft. DE filter
Hayward chlorinator
Jandy propane heater.

 

[JohnKrupp]

Is the flow poor even before the air bubbles show up?

 

[monzeez]

Is the flow poor even before the air bubbles show up?

Yes, and if I prime pump with multi-port in filter or recirculate, the strainer never fills up. I have to prime in waste, fill the basket and then change to filter.

 

[mas985]

checked impeller for debris

Did you take apart the pump (i.e. remove motor from wet end) when you did this?

Do you know what the filter pressure difference is between when it was running well vs now?

 

[pool&spatech]

The most restrictive valve setting other than "closed" is "filter" weak suction and return flow back to the pool would be noticeable if the filter was very dirty and needed back washing or filter service.

The least restrictive setting is "waste" this is where you noticed a powerful flow from the pump, which pretty much rules out the pump for the most part.

The next setting is "backwash" as the 2nd least restrictive setting, you also said the pump flow was strong.

The 3rd least would be "recirculate" this setting bypass's the filter completely, and should be less restrictive than the "filter" setting, and should be similar to how the pump works in "waste" and "backwash" only slightly more restrictive because it has to circulate through the pipes to and from pool.

Because "filter" and " recirculate" according to you, react the same way, and are both weak when compared to the other settings is unusual, the only setting that should cause the weak pump operation regarding flow to be noticeable, is "filter" and the reason would be due to the d e filter itself being extremely dirty ( i am not saying its dirty, i am just saying )

What i am getting at here is a restriction in the valve, or beyond, must exist because the flow weakness you describe is the same on both "filter" and "recirculate" both settings seem to be unable to to move any water because of some blockage, "recirculate" should be noticeably less restrictive than "filter"

Is there an accurate, working, pressure gauge on the filter or multi-port valve?
If not you need one, if there is, what are the psi readings when in "filter" and "recirculate"

You also mentioned how you prime the pump on "waste" setting, then switch over to "filter". When in "filter" there's not any change, or flow improvement from doing this, just the same weak flow, right?

The pump will act like you describe if there is some blockage choking off 80-90% of the return line back to the pool, does the water in the pump when viewed through the clear lid just look like its sitting there, hardly doing anything, when on "filter". And when on "waste" does it appear when looking through the lid there is a strong, aggressive, normal movement of water? if the pump only has 10% or so left that's unrestricted in the line to push water through, also means its only able to suck in enough water proportional to its ability to push through that 10%.

Both "filter" and "recirculate" should not be as equally restrictive as you describe, to me this indicates an obstruction or restrictive passage somewhere between the valve, and the return line back to the pool.

I notice you have a heater on the pool....