Need help with suction side leak. Hoping I don't have to dig!

[popeyejack]

I have searched the forums and haven't seen this exact situation. If it has been covered before please forgive me. I have an 18' by 36' inground pool with a 9' deep end; Hayward Superpump; 1 skimmer line; 1 main drain line. Looks like inch and one-half pvc pipe.

So, here is my problem: with both the main drain line and the skimmer line open(each has an independent pvc valve) there is no visible air leak. With just the main drain line open there is no visible air leak. When i close the main drain more than half way I get a sudden rush of air into the
pump basket. There is so much air that within a few seconds the pump basket is half air and the pump is barely able to maintain prime. Otherwise there doesn't seem to be a problem. I am seeing no noticeable loss of water anywhere. I have not found a leak above ground yet but I am hoping that is the problem and I don't have to dig up the concrete to get to the leak. It doesn't seem to me that it could pull that much air from an underground leak, but I am not an expert. I thought at first that I may have an obstruction in the line but water is flowing through it. I tried using water pressure to clear the line...it flows through o.k.. Now I am wondering if I have a partially collapsed line instead and it is starving the pump.

Thanks for taking the time to read this. Any input would be appreciated.

Mike

 

[Richard320]

I'd look for low water level or a stuck weir (That's the flapper thing) on the skimmer. Take a look inside the skimmer and have someone else move the valves. Do you see a vortex forming? If so, that's where your air is entering. Always start with the simplest things first!

 

[jblizzle]

Welcome to TFP!!!

Silly question, but after running with only the main drain, you did open the skimmer valve back up before starting to close the main drain right? If you did, then clearly there is some kind of air leak either in the skimmer line ... or maybe the main drain valve is leaking when you close it (I am not a fan of PVC ball valves).

 

[toofast]

Silly question....is this NEW after recently opening ? (even though you may not close based on your location)

Reason I ask, is I had this JUST happen to me, I was freaking...turns out the air just took a LONG TIME to completely get out. Now all is fine.

 

[duraleigh]

popeye jack, my system does something similar that may give you a clue. I, too can close skimmers or another line (main drain) independently.

If I restrict the total intake too much, (i.e. close one completely and start to close the second one) The power of the pump breaks the seal on the pump basket lid and air rushes in. So my issue is simply lack of adequate source water to keep the pump primed but the suction of the pump is powerful enough that it breaks that seal and sucks air.

There is no fix unless you want to redo plumbing and make a valved bypass around your valves.

 

[Perry Whitlock]

I just replaced my suction piping and installed a 3-way Jandy valve this weekend. Those pvc ball valves can do some crazy things. When my main drain suction valve was open it sucked enough air to displace nearly all the water from my cartridge filter overnight. When closed, the valve did not leak at all. This was not easy to find. You could not hear it and it did not leak water with the pump down. I was able to seal it with gel shaving cream around the valve handle and stem and after a while the air purged out of my pump.

 

[popeyejack]

Thanks for all the input guys. I am trying to rule out everything else before I dig.

Richard....The weir is working and there is plenty of water. When I have the skimmer line and main line open and I close the main past halfway, that is when I get
the sudden rush of air into the basket. When I look in the skimmer at this point there is plenty of water and no vortex.

jblizzle....I have both valves open and then close the main valve. I don't care for the PVC valves either. Especially since everything is glued together with no couplings and no room was left to cut and splice without replace all the plumbing from the ground up. I have tried pouring water over all the joints while it was sucking air and don't see an improvement.

toofast..Yes this is just after opening this year. This problem started to a smaller degree last year but is so bad this year that I can't get enough suction to the skimmer to run the suction side cleaner. When I put my hand down in the skimmer and cover the pipe opening I feel good suction but apparently not enough.

I just wouldn't think that it would pull this much air this fast if it was an undergound leak....that is why I was kind of leaning to a partial pipe blockage or collapse.
I was hoping someone would tell me I am wrong.

 

[Richard320]

I just wouldn't think that it would pull this much air this fast if it was an undergound leak....that is why I was kind of leaning to a partial pipe blockage or collapse.
I was hoping someone would tell me I am wrong.

Well, it could also be a partial clog. I just lost a wheel off my vacuum and sucked it up. It got hung up in the hose nipple and all the sudden my pump started making noise and lost pressure, yet it was still vacuuming. It looked like air in the pump basket, but when I bled it later, hardly any came out. Maybe something got in the pipe? You could always try shutting everything off, set it to skimmer only, then stick a garden hose in the pump inlet from the strainer side and seal it with a rag and try backwashing. All it would take would be one rock or matchbox car or vacuum wheel to restrict 75% or more of the pipe.

 

[popeyejack]

Thanks Richard, I'll look more in that direction. It would be great if it is something that can be cleared from the pipe.