Why is my spa draining when I turn off my pool pump?

PSC Ep. 79: Why is my spa draining when I turn off my pool pump?

In today’s episode of Poolside Chat, Rob and Matt tackle another common swimming pool question: 
Why is my spa draining when I turn off my pool pump?

Usually, the spa sits above the water line of the pool so if something goes wrong the water from the spa will drain out, but as to the cause as for why that would happen, the most common would be a check valve. There’s a check valve that helps keep the water in the spa and sometimes debris will get stuck in the check valve or the check valve will just go bad. In most cases you can open up the check valve and take a look at it, there are flapper style valves, you could just replace the flapper, or you might have to replace the whole thing. That’s the number one cause.

Some other reasons why there are diverter valves that control the spa suction if that’s left open or even partially open when the pump shuts off. It’s going to drain back out to the pool.

Within those diverter valves there’s a gate, and over time that gate could wear out, or the seal on that gate could become damaged so you might have to replace the internals in that valve. Another reason could be a bad actuator; maybe the actuator died when the gate was still left open on the suction side for the spa, so you’d have to replace that actuator.

Finally, you could have an air leak. Normally if a pool system is perfect, it’s sealed so that the water won’t drain out from the pump or anywhere else when it shuts off, but if there’s an air leak, it loses that seal and everything floods back to the pool. That’s another reason why your spa could drain out.

 

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22 thoughts on “PSC Ep. 79: Why is my spa draining when I turn off my pool pump?

  1. Spa losing water. Have had leak detection and a 30 years experienced pool co. come out and it still has the same problem. They have addressed items discussed in video. Leak detection company could not find any leaks. He said it was posssible I have a pin hole leak that he missed. Both companies are coming back out separately to try and solve problem

    1. If two real pros have come out there to take a look at it to diagnose and are still flummoxed, there is not much I can further deduce. Troubleshooting an issue like this is very difficult doing it blindly. I would need to be able to see the equipment, even hear it determine where to check next. Plumbing is not cookie-cutter form, there could be an oddity to your plumbing causing the problem.

  2. Can you tell me why my spill flow over into my pool isn’t spilling over like it should? It is slowing running out.

  3. After leaving our pool pipes wrapped and pumps/power turned off with the ice storm across Texas the last few days, our spa started draining today and the pool water level has risen. Is this common when the pool pumps are off or freezing temperatures are involved for several days? Thank you for your help!

    1. We are in Florida, so I have even less experience in freezing temp than you do. But did you receive any snowfall that may account for higher water levels in the top? And as Rob brought up in the article, have you checked your plumbing for any cracks or leaks that could account for this?

  4. Hello my spa drains to the pool level when I set the pool in suction mode (suction side spa). This occurs when the pump is running as well as when the pump is off. When the pool suction side is pool side the spa does not drain. Any ideas as to why?

    1. Everything we say in the video regarding valves can still apply to your situation. Look for leaks in the basin. I am unable to pinpoint that issue from that description, which is why we provide a list of things to check.

  5. My spa is draining down about 4 t0 5 inches each night. Yet it does not appear to be draining into the pool. The pool is at the same level when the pump shuts off at night and in the morning. The spa is down and when the pump goes on in the morning the autofill kicks on for about an hour. Then its off the rest of the day. I think the spa is leaking over night but where? Help!

    1. The first question, did you look at any of the plumbing features we mentioned in the video/article? If not, then you should start there.

      Second question, does it drain down to the same level every night? If so, then you probably want to start looking for issues around that plain in the spa’s basin or pipes.

  6. Hi I’m a new pool owner and my pool is loosing water then the system is running and when it turned off it doesn’t but the spa does and vice versa. When the system is running the pool losses water and the spa doesn’t. Any advise??? Please help

  7. My spa loses perhaps 3 to 5 inches overnight but stays above the jets which is approximately at pool level. The pool tech is confused because if it was a check valve normally it would lose water to a point of equalization with the level of the pool. Any ideas?

  8. Hi, my pool was draining all the water except maybe a foot of water, or until it reach the level of the pool water level when I turned off the pump..and yes I changed the check valve flapper… that worked for a couple of days…and yes it was draining back into the pool..what’s happening now is that the spa only drains like 10 inches at the most but what I’m noticing is that my pool is draining more than a few inches every day… if I divert the water from the spa and just have it circulate to the pool then the pool does not lose those inches of water…So I am assuming my pool does not have a leak…my question is if I change the check valve on the spa and the spa only loses a few inches and supposedly the water is supposed to drain back into the pool, I shouldn’t be losing so much water that my pool water level drops below the tiles…where is the water going?

    1. If you have checked all the valve, then it sounds like you have a leak in your spa. A spa shouldn’t lose 10 inches of water; plus, if your pool is affected as well then it definitely sounds like a leak. Because I can’t see your system or its plumbing, you may want to have a professional come out and take a look.

  9. My Spa drains all the way down at about 2-3 inches a night until it drains to the bottom of the spa and then stops draining with the water in the drain cup only. It’s hard to tell if it is draining back in the pool. Your thoughts please

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