Sudden air in my returns?

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Needsdecaf

Well-known member
Jun 28, 2014
176
The Woodlands, TX
Hello all:

New pool, build thread is linked in my signature. Had it up and running about 30 days.

My PB stopped by on Friday to start up my salt water generator. Since then I have noticed constant spurts of air from only TWO of my four returns. They are both on the same side (far side) of the pool in relation to my equipment. I have been told that SWG causes bubbles, but this is a "spurt....spurt....spurt....spurt" every 3-4 seconds, and it's kind of a big burst. It sounds annoying when you're under the water.

I have tried everything to bleed air, including opening up both pump covers, and bleeding air out the bleed valve on the top of the filter. The PB says he didn't open up the salt cell or touch anything, although he DID state that he was running the filter on drains only, not skimmers, to suck down some of the salt.

Any thoughts?
 
Is this happening on less that full speed? If so, it is normal. The gas bubbles from the SWG collect in the pipes and then burp out occasionally. The flow rate is not sufficient to continually purge the gas. This happens to mine on low speed as well. On full speed, you should just get a lot of little bubbles.
 
That is a bit more air than what would be caused by an SWG so it is probably an air leak. Do you see air in the pump basket?

Also, because you are on main drains only, the suction could be quite high in the pump basket so it might be drawing in air.
 
The only reason that the air is coming out of only two of the returns is probably because those returns are higher than the other returns and on low speed, the air follows gravity as well as the flow rate. So that part is not that meaningful and has more to do with the flow rate than anything else.

So what happens when on full speed? Also, what is the filter pressure on full speed?

After running on high speed for a few minutes and then dropping down to the lower speed, does it take some time for the bubbles to show up again or is it immediate?
 
So my pump runs at 30% during the late morning and early afternoon, and back up to 50% at 2:00 PM. When I went outside at 2:00 PM, there were bubbles coming out of the returns. There were also bubbles in the pump basket.

I turned everything off and ran the following experiment:

1. Opened the cover on the pump basket and allowed water to drain down.
2. Turned on pump. Pump automatically goes to 100% power at times during startup (have not figured out this logic). In any event, that time is usually 2:30, and so it was. At this time pressure was 22psi.
3. Pump down to 70%. Psi dropped to 16 psi. Ran for 6 minutes. No bubbles in the basket, no air coming out of returns.
4. Pump down to 50%. Psi dropped to 6 psi. Ran for 10 minutes. Tiny bubbles in the basket, air coming out of returns.
5. Ran pump another 10 minutes. Tiny bubbles (like 5) still there, but no more. Amount of air did not change.

Have not reduced pump speed as 50% is it's normal afternoon run speed.
 
The air in the pump basket indicates a suction side air leak somewhere and probably what is causing the bubbles although the SWG may be contributing. If you want to make sure, shut off the SWG completely and rerun your experiment and see if the results are the same. But either way, you still have an air leak in the suction side somewhere.
 

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OK, so now I have a lot of air in the pump basket. However, there is NO air coming out the returns whatsoever.

More tellingly, the SWG is off.

How could I all of a sudden developed an air leak on the suction side? Or maybe it was there all along and I didn't notice air in the basket because I didn't have air from the SWG?

Oy vey.
 
I would get the builder involved and have them do the leg work to figure it out. If they can't figure it out then fight, if you have to, to get a leak detection company involved to figure it out, if it is a leak. The builder should be able to run a pressure test on the pipes to rule out a leak in the pipes. Don't let them off the hook until you get this figured out.
 
Spoke to my PB. He is still researching the info on the SWG / air. But I will say that he is pretty adamant about air building up in the basket from the variable speed pump. He notes that on lower speeds, air will gradually build up in the basket, but will be pushed out and stay out when pump is on high volume.

His statement mirrors my observations from yesterday. Sunday night there was all kinds of air in the basket chamber. Yesterday when the pool had just completed a 3 hour run at 70% speed, the air was all but gone, and there were some small bubbles. By last night, the bubbles were larger again.
 
What you are describing is normal but from what I understood about your situation was that you were also get air out of the returns on low speed with the SWG off or did I misunderstand.
 
Ok then the SWG is clearly causing the air out of the returns which can be normal although from the video, it looked like a lot more than what I am use to.

Also, after running on high and then switch to low, if it takes a long time (hours not minutes) before air builds up in the pump basket, then it is probably a common condition. Either a very slow leak or out gassing. But if you have a high speed cycle each day, it shouldn't be a problem.
 
Did you bleed your cartridge filter. Mine has a bleeder on top of it which you open to let pressure out before cleaning. After I clean I open it up with the pump running until you get a constant flow of water. Forgot to do it this year after my first clean and I had a lot of bubbles.
 

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