Pump basket drains when pump is off

[kodiak1120]

Is it normal for my pump basket to drain water when the pump is off? In other words, the pump runs fun and the basket fills up with water when it's running, but once it's off the water level inside the pump basket drops. So the next morning, the water in the pump basket is down a few inches and it has to re-prime when it starts running again.

I'm having an issue with high pressure in my DE filter. For some reason, my pressure goes up quickly. I was backwashing every few days and I thought maybe I was adding too much DE, so I started backwashing and not adding DE. Even doing that, the pressure would go back up again in a day or two. Even with no DE being added after several backwashes, the pressure still would go up after a few hours.

Last night I took apart the filter and I didn't see anything obviously wrong. The filter was about 95% free of DE, so my backwashing is working fine. I even took apart the manifold to make sure there were no clogs, etc. All of the piping and everything inside the filter looked good. The air hose on top of the filter was very clogged though with DE and some type of pool toy that apparently disintegrated and made its way into the filter. It looked like blue and orange foam type material. There wasn't a ton of it, but it was caked around the air hose inside the filter. I read that when that clogs, it can cause pressure issues so I'm going to see if that fixes the issue.

My research has suggested that an air leak on the pump side can cause pressure issues because the air builds up inside the filter and increases the pressure. After thinking about this morning, it occurred to me that the pump basket should probably remain full of water even when the pump is off and the fact that its not probably means I have pretty substantial air leak somewhere and that may be causing my pressure problems.

I did replace the gasket for the pump basket lid last year or the year before that and I applied magic lube to help seal it, but maybe the lid is bad? I need to take a closer look tonight.

 

[Richard320]

I see two problems

1) Filter clogging quickly.
2) Pump basket empty overnight

First thing: you should never run a DE filter without DE. You run the risk of damaging the grids. That said, if you're loading up so bad that only a backwash helps, there's something in your water that's doing it. I suspect a nascent algae bloom. For now, you're likely at a stalemate where you're killing algae at the same rate it can grow so you end up with a neverending supply of dead algae to strain out. You probably need to SLAM Process

One of two things is happening to cause the pump to drain. The simplest and most common is that you're sucking air when its running, a big gas bubble forms in the tank, and as soon as the pump shuts off, it expands because it's no longer under pressure and pushes the water out. It could be as simple as low water or a sticking skimmer door. Look for a vortex in the skimmer when it's running.

One way to tell is to open the air bleed while the pump is on and let any air escape, then shut the pump off for the night. If the pump stays full, you have a suction side leak.

Less likely but still possible is a deformed O-ring inside the air bleed. Under pressure, things seal up. But when there is no pressure it can let air enter. If the test above passed, the next night, do the same, but slip a balloon or the finger of a latex glove over the air bleed. If it's leaking, it will suck the balloon in as the water level drops.

 

[kodiak1120]

Thanks for the response... I should have been more clear, but the filter isn't clogging up quickly. I thought it was and that's why I wasn't adding DE, but when I took it apart, it was relatively clean and there was almost no DE. Thus, I think the pressure problem has to do with air getting in the filter, as opposed to algae or something else clogging things up.

Regarding the air leak, the water level was low, but I added water last night and the problem persisted. In fact, when the pressure goes up in the filter, it doesn't even really draw water at all because it's not pushing water out.

I'll give the method you suggested a try tonight. I'm thinking I have a suction side leak, but I'm just not sure where.

 

[Richard320]

Thanks for the response... I should have been more clear, but the filter isn't clogging up quickly. I thought it was and that's why I wasn't adding DE, but when I took it apart, it was relatively clean and there was almost no DE. Thus, I think the pressure problem has to do with air getting in the filter, as opposed to algae or something else clogging things up.

Regarding the air leak, the water level was low, but I added water last night and the problem persisted. In fact, when the pressure goes up in the filter, it doesn't even really draw water at all because it's not pushing water out.

I'll give the method you suggested a try tonight. I'm thinking I have a suction side leak, but I'm just not sure where.

That's not the way it works. If you were to screw a short length of pipe to the outlet of your pump and screw a pressure gauge into the side of it and turned the pump on, you'd have water everywhere. and the gauge would read zero. Choke that pipe down to half the diameter and you'll get a geyser and start seeing pressure on the gauge but there would be much less water hitting the ground around the pump. Choke it all the way off and you'll get really high pressure and none on the ground.

If the pressure gauge is climbing, it's due to restricted flow on the outlet side of the pump. If you had a restriction on the intake side you would see low pressure.

The air bubble inside will expand or contract depending on the pressure against it. It does not create any pressure. Only the pump creates pressure, and only if there is some resistance to flow.

 

[kodiak1120]

Well I fixed it by replacing the Jandy valve immediately before the pump strainer. That valve allows you to draw water from one skimmer box or the other. I noticed when I turned the pump off, I could hear water draining and air moving from around the Jandy valve. I took the top off of the valve and I noticed small cracks around each of the screw holes:

I ordered a new Jandy valve and installed it today. I noticed an improvement right away. I opened the bleeder valve on top of the filter and let the air out and then closed it. I now have zero bubbles in my pump strainer and it no longer drains. I had it running for a few hours this evening and the pressure stayed at 11 psi. Also, even when it's off for a few hours the pump strainer basket stays full. It used to look like rapids inside there when the pump was running and would drain as soon as I turned it off. No I get no bubbles and it stays full. Here's a shot of the new Jandy valve:

It's kind of hard to see, but here is the pump strainer with no air bubbles. This was taken while the pump was running:

 

[kodiak1120]

That's not the way it works. If you were to screw a short length of pipe to the outlet of your pump and screw a pressure gauge into the side of it and turned the pump on, you'd have water everywhere. and the gauge would read zero. Choke that pipe down to half the diameter and you'll get a geyser and start seeing pressure on the gauge but there would be much less water hitting the ground around the pump. Choke it all the way off and you'll get really high pressure and none on the ground.

If the pressure gauge is climbing, it's due to restricted flow on the outlet side of the pump. If you had a restriction on the intake side you would see low pressure.

The air bubble inside will expand or contract depending on the pressure against it. It does not create any pressure. Only the pump creates pressure, and only if there is some resistance to flow.

In researching this issue, I've seen numerous references that state air leaks before or at the pump can cause an increase in pressure because the air builds up in the top of the filter. For example:

How to Reduce High Pressure in Your Pool System - INYOPools.com

I understand what you are saying, but it makes sense to me that if you keep adding air to the filter, you're eventually going to create more pressure, just like if you kept adding more and more water. Water doesn't cause pressure to increase because no matter how much you add, it will be able to escape through the plumbing. I think the difference with air is that it can't escape because it goes up (as opposed to down) and just collects in the top of filter. After a while that has to result in an increase in pressure inside the filter.

In my case, I had a substantial air leak. My pump strainer would drain in about one minute after turning the filter off. I tested and confirmed this by opening the bleeder valve before I replaced the Jandy valve and leaving it opened. When I did that (and allowed the air to escape), my pressure remained constant. While it was opened, I could feel a constant flow of air. So that tells me that the problem was air building up and having no were to go, thus increasing pressure inside the filter.