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:
- 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!
- 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).