Tiny Air Bubbles from Return Jets

jroberie87

New member
Oct 1, 2020
4
Sarasota, FL
I recently purchased my first home with a pool so this is my first foray into pool operations. For my work, I do mechanical and plumbing design work so I am fairly familiar with the general principles of plumbing piping and pumps. For an overview of the system, the house we purchase has an in-ground pool (approx. 15,000 gallons) with a variable speed pool pump (Jacuzzi J-VSP250), DE filter (Hayward Perflex EC65A), and a solar heating system. I noticed tiny air bubbles coming from one of my four return jets so I immediately think air leak. Being busy with the move in right now, I have hired a pool service company to maintain for the first few months. They sent out their service manager to take a look at resolving the issue. After 45 min. to an hour of time spent checking all possible air leak locations, he was unable to locate. He stated that while possible their is a small air leak in the below grade plumbing that he doesn't believe this is the case. I should also mention that our pool has a dedicated sidewall vacuum line that remains closed unless being used with our automatic vacuum. Through his investigation, he came to the conclusion that he believes the pump is a little oversized for the incoming lines and those lines are restricting flow a bit. The way it is piped into my pump is (2) separate 1-1/2" lines from the skimmer and vacuum line turn up from below grade and connect at a 1-1/2" valve and 1-1/2" line into the pump. The maximum flow through a single 1-1/2" line is 42 GPM and the default flow rate on low speed for the pump is 52 GPM. With just the skimmer line open and vacuum line fully shut, the pump primes a little slower and once down to low speed is when the air bubbles appear and the basket at the pump is only about half full. If you open both the vacuum line and skimmer line to fully open (so two 1-1/2" lines instead of just one) the pump primes with no problem and can hold that prime once it reverts down to low. The pump itself is running normal without any concerning noises and the guy tells me the pump is pretty robust and I am not doing any damage to it even with the air bubbles. I do not care about the air bubbles unless they are doing damage to my pump which I am told they are not.

I am not necessarily looking for an answer or fix, but just thoughts and suggestions on the above diagnosis as the plumbing designer in my wants to understand everything going on. Thanks for any comments or input.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,306
Laughlin, NV
Welcome to the forum!
If the pump basket is not filling, you have a suction side air leak. The most likely spot for that is the gasket on the pump basket lid. Try lubricating it with pool lube. It needs to be a non-PTFE silicone lubricant.
Another source of bubbles can be a Salt Water Chlorine Generator. But you did not mention one and the fact your pump basket is not filling with water when the pump is running points to a suction side air leak issue.
I suggest you read ABC's of Pool Water Chemistry.
 

jroberie87

New member
Oct 1, 2020
4
Sarasota, FL
Thanks for the information. The technician checked all the gaskets, valve, and above grade plumbing joints with no sign of air leak. All gaskets were lubed. The pump basket does fill up when both the vacuum and skimmer lines are fully open simultaneously. When just the skimmer or vacuum line is open while the other is closed, it will mostly fill when priming, but then slowly regresses to about half full when priming is over and pump turns down to low speed.
 

Homebrewale

Well-known member
Apr 21, 2020
305
Apex, NC
Thanks for the information. The technician checked all the gaskets, valve, and above grade plumbing joints with no sign of air leak. All gaskets were lubed. The pump basket does fill up when both the vacuum and skimmer lines are fully open simultaneously. When just the skimmer or vacuum line is open while the other is closed, it will mostly fill when priming, but then slowly regresses to about half full when priming is over and pump turns down to low speed.
How is the technician checking the valves? Did he use the water test on the suction side to find any air leaks? I just had a ball valve on my system start leaking air. I found it using the water test. I'll be replacing that ball valve in the next week.