Suction Side Leak Help

[mikelehen]

I seem to have a significant suction side leak this year and I'm worried it's underground, but I can't quite make sense of all my symptoms.

For background, I had my pump and valves replaced last year by a pool professional and everything ran great last season. I kept my pool "open" over the winter rather than winterizing (I live in Seattle and we don't get super cold winters). But when I went to start getting the pool in swimming shape again this season, I discovered a couple symptoms:

• The pump basket only fills ~50% (the water is just slightly above the outlet port and sloshes around). (video here)
• At ~1700 RPM (my standard "filtering" RPM) I get very slight bubbles from the return jet and some air buildup in the filter.
• At higher RPMs (e.g 2500), I get major bubbles from the return jet and substantial air in the filter (e.g. running for ~5 minutes might build up ~5 seconds of air to bleed out)

I have no other symptoms that I know of (the pump does prime okay, I'm not losing water, etc.)

This seems like a suction side leak, but I've had no luck finding the culprit. Here's a picture of my plumbing for context:



Things I've tried:

• Clean, inspect, and re-grease all of the O-rings on the suction side:
  • The pump lid (multiple times since this seemed like the most likely culprit)
  • The pump drain plugs (and I tried swapping them since there are two identical ones)
  • The union to the pump
  • The Jandy 3-way valve
• I tried pouring water from a hose over the pump lid and joints / valves, looking for a change in the air in the pump basket, but wasn't able to detect anything.
• I verified pool water level is fine and skimmer isn't vortexing or anything.
• I tried using the smoke from an incense stick to find any joints sucking air. Not sure if this is a viable technique (found it on youtube), but it was a failure for me because the pump fan generated too much air movement in the pump house.

Given that I can't find a leak in the pump house I'm worried that it's under the concrete. I have some large trees around my pool and I'm imagining their roots encroaching on one of the pipes or something. But I did one more experiment that has me scratching my head. In addition to the pool, I have a very small (maybe 300 gallon) "spa" that I never use. But my plumbing is set up with two 3-way valves, one on the suction and one on the return, to divert between the pool and the spa. So I did some experiments changing where I'm pulling and returning to:

from	to	psi	air in return and filter	pump level
pool	pool	5	yes	50%
spa	pool	5	no	80%
pool	spa	10	no	80%
spa	spa	10	no	80%

So basically it behaves significantly better in any configuration other than "from pool, to pool" and two things don't make sense:

1. When pulling from the pool and returning to the spa, I expected to still get my leak symptoms of air in the return jet and in the filter and pump only filled ~50%, but I did not!
2. Even when pulling from the spa and returning to the spa, the pump still had a large air bubble at the top. It was *way* better than when going pool=>pool, but there was still maybe an inch of air at the top.

You'll notice that the psi is much higher when returning to the spa (10psi instead of 5), so I think there must be a higher head and am thinking that may explain #1. But the fact that recirculating the spa still leaves me with air in the pump basket makes me wonder if I've missed something and the leak is in fact in the pump house, affecting both the pool and the spa.

Anybody have any theories or other experiments I should try? Unfortunately I'm thinking my next step may be to call a professional (the local pool store recommended American Leak Detection).

 

[Texas Splash]

One thing for sure, not too many people provide such a well drawn-out illustration of their symptoms and issues. Good job on you. Since you've done so much already, I'm going to toss a couple things out there in a "hail Mary attempt" for ideas that I didn't see in your history:
1 - Since everything worked perfect at the end of the season, if there any chance you might have a partial blockage? The restriction of water flow might be misleading you to thinking there was a suction leak?
2 - Have you tried shutting everything down for a day or two (increase FC a bit first), to see if the water level drops? If it does, then perhaps close (isolate) some water routes to try and see which area or side (pool/spa) effects the water loss? Since we expect a suction side leak to draw-in air while running, if big enough it can leak water when the suction is not applied.

That's about all that's coming to mind since you've done so much already. I'll return if I think of something else. Others might have a thought or two as well.

 

[atttech-2]

long shot based on your efforts so far but you could try shaving cream everywhere you can on the suction side, see if you get a hole sucked into the foam (not my idea one of the more senior members suggested it in a post I read a while ago can’t recall who to give credit).

 

[mikelehen]

Thanks guys! I'll do the "pump off water level" test and experiment with shaving cream over the next few days and report back. Both good ideas.

An obstruction is an interesting idea I hadn't considered. I can't think of anything that would have caused an obstruction. My skimmer basket and main drain cover are both in good shape so I can't see anything big getting sucked in... but it does kinda' fit with the idea that it was running great last year. I'll have to go read the forum posts about obstructions and see if I can discover anything. Thanks!

 

[duraleigh]

That is a very thorough description of your issue. I want to encourage you just a bit by saying that it certainly can be an underground leak but it is rare that it turns out to be the problem.

Since adjusting the three way valves causes a difference in the flow, I would be suspicious of the three way on the suction side. In other words, why does turning that valve make a difference in your flow to the pool? There may be a gasket issue with that valve or, if I understand your setup, you may have a partial blockage on the suction side that only comes in to play when you select it.....does that make sense?

 

[mikelehen]

I actually get similar flow (well, filter psi anyway) regardless of whether I set the suction-side valve to pull from the pool or the spa, so I think it's probably okay? The valve that makes a difference is the return side (whether I'm pushing to the spa or the pool), which I think can be explained by the jets on the spa causing increased head. In any case, thanks for the encouragement!

 

[Curiousgeorge]

Pull the motor from the housing and check the diffuser gasket. While u have access to it clean out the impella as well.

 

[Curiousgeorge]

Also....is there any water or leaks from the bottom of your pump.....sometimes a bad pump seal leak can cause those same symptoms.
Make sure to inspect the housing completely. Small unseen cracks can cause havoc too.

 

[duraleigh]

I actually get similar flow (well, filter psi anyway) regardless of whether I set the suction-side valve to pull from the pool or the spa, so I think it's probably okay?

Your table above indicates that you get air when pulling from the pool but none when pulling from the spa. If that's true, that should be a big "bazinga" in that now you have identified an air source somewhere between that valve (or the valve) and the spa.

Please don't waste time looking for a (pump running) air leak on the pressure side of your system........that doesn't happen.

 

[mikelehen]

Thanks guys. I left my pump off for two days with the solar cover on and lost almost an inch of water, so I think unfortunately I probably have a suction-side leak in the pipes under the concrete. :-/ So I'm thinking it may be time to give American Leak Detection a call. Hopefully they can confirm my findings and narrow down the location.

 

[mikelehen]

Welp, American Leak Detection came out, pressure tested the skimmer line, found that it was leaking, and (hopefully) pinpointed the spot under the concrete where the leak is. Took about an hour and a half for them to find the spot (they said it was a tough one). They charged $650 for testing everything they could get to from outside the pool... An extra $150 if I wanted them to dive the pool and check the main drain and the pool itself. More expensive than I would have liked, but they definitely seemed thorough and experienced. Hopefully they found the right spot!

 

[Texas Splash]

Sorry to hear about those troubles.