Pump stops moving water after ~10 minutes

[rdtoutopia]

My husband and I bought a house with a 28' round above ground pool in March of this year, and we've learned so much from this site already. Neither one of use has any experience with pools, and we are really stuck with a problem we can't figure out.

I'm sure I'm leaving out some vital information, but here's what we know:

We are not sure how old any of the equipment is, or how it's been maintained.

The pump (Hayward PowerFlo LX 1.5 hp) is priming properly, and runs well, moving water, for about 10 minutes. After that, the suction in the skimmer and the return flow drop to almost nothing. The motor sounds like it's running fine, not struggling or cutting out.

The pump basket stays full of water, with one large bubble moving around on the top, and the filter stays pressurized. We have checked the skimmer, all hoses, connections, etc. for blockages and have found none. We took apart the motor to check the impeller and it was completely clear of debris. The filter looks clean to our untrained eyes - white inside the folds with some dirtier looking spots on the edges. (the filter material is light brown/gray.) No obstructions in the filter tower we can find.

Every time we take apart the thing and put it back together it will work well again for a few minutes, but then drop off again. The only thing that seems amiss at all is that the connection between the pump and the cartridge tower (not sure what it's called) gets wet to the touch where it screws together, but it has to run for hours before it actually drips.

Does anyone have any suggestions on what to try next? Do we need a new pump? It was so sparkling clean when we first opened it, and now it's slowly turning green without the pump to move the water.

I appreciate your help!

 

[JohnT]

Welcome to TFP!

What are your pressure gauge readings when you start the pump and when the water stops moving?

Have you cleaned or replaced the cartridge?

 

[dattia]

Is there a gasket in the lid to the pump strainer? Check it to see if it is in good shape and apply silicone pool lube to the gasket (O-ring).

 

[cramar]

Sucking in air at one of the hose connections? Just a thought.

 

[rdtoutopia]

The pressure reading on the cartridge is about 19psi, both when it is working well and when it's not. We hosed the cartridge off, since it had cobwebs from the shed but didn't replace it. It doesn't really seem dirty, but then again I'm not sure at what point they need replacing.

There is an o-ring - we have taken it out to inspect and it seems fine. Cleaned up the old gunky lube and applied new stuff. Did the same with the gasket at the top of the filter tower.

How could we tell if there is an leak? I read about pour water over the connections, but what should we look for? Bubbles? The return force to suddenly rise?

Thanks!

 

[rdtoutopia]

Thinking about it, something unusual with the filter pressure is that as soon as the pump is unplugged, the pressure drops to zero. There is nothing left to come out of the release valve. But there also isn't water leaking from it anywhere while the pump is running.

 

[dattia]

When my Hayward Power-Flo Matrix was having problems, the water just seemed to vibrate in the pump... having the large bubble moving around was always a good sign for me. Have you backwashed at all?

 

[rdtoutopia]

I haven't backwashed. I'm not sure how to do it. When I've seen it mentioned there is usually a lever or knob to turn to backwash but I don't have anything like that.

 

[JohnT]

The pressure reading on the cartridge is about 19psi, both when it is working well and when it's not. We hosed the cartridge off, since it had cobwebs from the shed but didn't replace it. It doesn't really seem dirty, but then again I'm not sure at what point they need replacing.

There is an o-ring - we have taken it out to inspect and it seems fine. Cleaned up the old gunky lube and applied new stuff. Did the same with the gasket at the top of the filter tower.

How could we tell if there is an leak? I read about pour water over the connections, but what should we look for? Bubbles? The return force to suddenly rise?

Thanks!

There's a mystery for sure. If the flow changes, the pressure has to change. Makes me suspect your gauge isn't able to register beyond 19psi. Maybe have someone hold their hand over a return fitting while the water is flowing and see if you get a pressure rise.

Loss of flow could show a pressure rise, meaning it's a blockage on the outlet, or it could show a pressure drop meaning it's a blockage or leak on the inlet side, or an impeller problem.