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Thread: Cause for spa draining into pool?

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    Cause for spa draining into pool?

    New pool, turned on the equipment the first time Fri, May 10. All ran fine; circulated pool/spa together, pool alone, spa alone, etc. No detectable equipment problems at all. Ran the Intelliflo VS mostly on 2350 or 3450 as I tried out different water effects, skimmer efficiency, and manual vacuuming.

    Tuesday, 5/21, I came home to find the spa about a foot low, and pool full (it was overflowing, but difficult to know that at the time due to massive rains that had hit that day.)

    When the plasterers were here they were short one eyeball, and one of the return lines was leaking when they cut the plumbing open so they had a plug in that line. Also, the blower had never been installed, and the blower pipe was capped off. On Monday 5/20 the builder came by, removed the plug and put the eyeball on; cut the blower pipe and sat the blower on the pipe. These were the only 2 modifications to the system from when it was operating properly.

    The return jet in question is in the pool, and is supposed to be plumbed in line with 3 other returns to the pool. In addition, the pool has a single, plumbed to the pad, return jet for a pressure cleaner, but is being used as a return jet. All this plumbing is 1.5". Two skimmers, and a double main drain are each plumbed directly to the pad in 2". There is also a separate 1.5 line that serves 2 bubblers, but it has been turned off.

    A single 2" return line runs to the spa with 6 return jets. A 2" suction line and 2" air line also serve the spa. Spa spills over into the pool. No automation system.

    As previously stated, on Mon (late afternoon) the plug was replaced with the eyeball, and the air line cut open and blower sat on. The blower was ran for a few minutes while equip was running. Early Tues morning I noticed the stone waterfall/ spillover from the spa was dry, went out to check the equip and saw that it was running, with water in the pump basket. It was still showing to be at 2350, but the suction and return was very weak (I checked the skimmer and return jet closest to the pad) so I shut off and turned the pump back on- waterfall began again, suction/return was back up and everything appeared to be working fine.

    Fast forward to 8 pm, returned home to find the spa about 1" low, and pool overflowing. Equip on, valves all set where I left them- suction 100% from pool (both skimmers and main drain open), return ~60% pool/ 40% spa, all jets in pool open, bubblers on beach closed. BUT pump is behaving the same as that morning- indicating running at 2350, water in basket, but virtually no detectible suction from the closest skimmer, and very, very slight return pressure from the closest return jet (which happens to be the one that had been plugged.)

    Shut off equipment and begin adding water to spa, but discover after a period of time that the water is ending up in pool. The water level in the spa is at the jets and won't go above them. Having the thought that maybe the check valve is bad, I set the return valves to spa off. The spa now begins to fill and no more water flows into pool.

    Builder comes by a couple days later (system has been off) and puts the plug back into the 'offending' return jet. He sees no visible problem with the check valve. I open up valves, 60/40 return to pool/spa, but leave equip off. Spa holds water for 4 hours. Turn equip on, run for 9 hours, everything holds. Next day I remove the plug in pool jet, and spa holds water both with the equip off and on. So, I have not duplicated the problem, which leaves me quite uneasy as to when it might rear its ugly head again.

    Anyone have any thoughts as to what could be going on? Or any tests I could run? Although the check valve seems to be the logical answer, what about the odd behavior on the pump, could a failing check valve cause it to behave that way? The spa drains have been set to OFF the entire time, so it seems that the water had to be coming from the spa jets, but with the pump on I don't understand how that could be- water should be running the other direction. Plus, when I turned the spa return valve to OFF, the spa stopped backflowing into the pool (pump was off at that time), which again points to the issue being in the spa return jets. Again, no automation, so nothing accidentally opening.

    Here's a drawing of how the plumbing is run. The return jet locations are indicated by a colored circle on the coping. The orange jet is the jet that initially had the plug, it should be plumbed in line with the red jets. I do not have the lines terminating at the right place at the equip pad, and the cross-overs, etc are probably not exactly right. The only 2 thoughts I have come up with are an intermittently bad check valve, and a plumbing line that got connected wrong.

    20k white plaster with blue quartz, IntelliFlo VS, Quad DE 100
    1000 gal spa with natural stone waterfall
    Beach entry with 2 bubblers. Pool built Spring 2013

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    JasonLion's Avatar
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    Re: Cause for spa draining into pool?

    Check valves can get debris lodged in them temporarily, allowing to spa to drain down but vanishing by the time you checked on the check valve.

    Another possibility is that one of the pool/spa three way valves doesn't fully close every time, but does close most of the time. That seems less likely, but I have seen it happen.

    Spa leaking down is almost invariable caused by a problem with either the check valve or one of the three way valves. The only other possibility is a significant leak in the spa that happens to feed into the pool, which is exceedingly unlikely and wouldn't magically go away.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Cause for spa draining into pool?

    Thanks Jason, I know that was a lot to read and wrap your head around what I was trying to explain.

    I do not see any evidence of a leak in the structure, the spa has not lost any water for 24+ hours while the system has been on pool only. I also do not see any evidence that the 3-way suction valve is not operating correctly since the spa has not lost any water while running on pool only.

    That leaves me with the check valve, which I agree is the most logical culprit. BUT, could the check valve be at fault if 1) the suction valve is preventing any suction from the spa (as determined above) AND 2) twice the system drained water from the spa while running. This is what gets me, with the pump on water should be being forced into the spa, and shouldn't that prevent any backflow through the return line?

    What do you think about the issue with the pump; it was set on 2350, could be heard running, had water in the basket, yet no detectable suction from the skimmer, and very little detectable return flow. Is it possible the check valve could have caused the pump malfunction? And is it possible for a pump malfunction to cause a suction through the spa return line while simultaneously maintaining a return to the pool?

    To reiterate, the spa lost water 2x with the pump on (both times the pump was found to be 'malfunctioning') and then continued to lose water with the pump off while trying to refill the spa. It took closing the spa return 3-way valve to get the spa to hold water.
    20k white plaster with blue quartz, IntelliFlo VS, Quad DE 100
    1000 gal spa with natural stone waterfall
    Beach entry with 2 bubblers. Pool built Spring 2013

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    Re: Cause for spa draining into pool?

    Follow up for anyone who may end up searching this in the future.

    The situation occurred a third time- suction/return low and spa began dropping. The Pentair rep came out and could find nothing wrong with the valves, or pump, although the filter was pretty dirty. Apparently, with an Intelliflo pump the filter is ready for cleaning at a 5psi increase, not the 10psi increase indicated in the manual.

    His explanation was that when turning off the pump some of the filter media would drop off the cartridges and upon turning back on the flow would have less resistance. I would then have better suction and return pressure for a period of time until the media was drawn back into the cartridges.

    The spa only drained significantly (to the return jets) one time. The other two times it only got as low as just below the waterfall. I had assumed I had caught it before it drained all the way. The Pentair rep felt like it would not have continued to drop on these two occasions, that it simply drained all it could through the waterfall and the return flow to the spa had stopped as the pool returns were the point of least resistance.

    His explanation for the time it drained down to the jets was that something had clogged the check valve and due to the low flow/ high filter psi a venturi effect was created pulling the water back through the spa jets and into the pool. Sounds far fetched to me, but admittedly I know very little about all this. I will say that since we cleaned the filter (4 days ago) I have not experienced any more drop in pressure or dropping of the spa level.
    20k white plaster with blue quartz, IntelliFlo VS, Quad DE 100
    1000 gal spa with natural stone waterfall
    Beach entry with 2 bubblers. Pool built Spring 2013

  5. Back To Top    #5
    Mod Squad jblizzle's Avatar
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    Re: Cause for spa draining into pool?

    What is your clean pressure and at what speed?

    We recommend cleaning the filter when the pressure rises 20-25% over the clean pressure.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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  6. Back To Top    #6

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    Re: Cause for spa draining into pool?

    10 psi at 2350, everything open. So yeah, at 16 I was a bit over 25%. Thing is, the Quad DE manual says clean at 10psi over starting.
    20k white plaster with blue quartz, IntelliFlo VS, Quad DE 100
    1000 gal spa with natural stone waterfall
    Beach entry with 2 bubblers. Pool built Spring 2013

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    Mod Squad jblizzle's Avatar
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    Re: Cause for spa draining into pool?

    You should be cleaning by 13 psi based on this forums findings. Waiting for 10psi is too much and did not make sense when you realize [s:12zy2q96]surprise start are[/s:12zy2q96] some start at 10psi and others may start at 25psi.

    Not sure if this would solve the problem your not though.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Cause for spa draining into pool?

    when you realize surprise start are 10psi and others may start at 25psi.
    hmm, don't really understand what this means?

    I will definitely be cleaning earlier now, just didn't know that I should per the mfg manual. According to the Pentair rep though, it's the design of the Intelliflo, and it's efficiency, that makes it necessary to clean at a lower pressure.

    And I certainly hope that was my problem- so far so good, keeping my fingers crossed!
    20k white plaster with blue quartz, IntelliFlo VS, Quad DE 100
    1000 gal spa with natural stone waterfall
    Beach entry with 2 bubblers. Pool built Spring 2013

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    Mod Squad jblizzle's Avatar
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    Re: Cause for spa draining into pool?

    Auto-correct messed it up. Basically a 10psi rise over a clean 25psi is a 40% rise in pressure. A 10psi rise over a clean 10psi is a 100% rise in pressure (which would likely result in VERY little flow making it through the filter at that point).

    The pump efficiency really has nothing to do with how often the filter needs to be cleaned. Any pump moving the water at the same flow rate would result in the filter getting dirty at the same rate.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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  10. Back To Top    #10

    Re: Cause for spa draining into pool?

    I had this problem with my pool when it was brand new. There were a couple of things that were causing this same problem.

    1) the check valve (sliding type) got some sand debris on the rubber, so it was not sealing when the pump turned off

    2) when installed, one of the automatic valves did not seal tightly when the pump turned off because the installer allowed some PVC cement to get into it. it didn't allow the valve to seat when closed

    I have a raised spa about 1' above the main pool and the water would drain from the spa back into the pool

    hope this helps you. It took me a while to find these. The pool builder at the time couldn't figure it out. He did supply the parts for my repair. For the automatic valve, I ended up taking it apart, looking inside and replaced the internal mechanism. The Check valve slider needed to be replace because the pitting from the sand didn't allow the valve to seat.

    hope this helps,

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