Surging air bubbles coming from jets

[mikemass]

My pool consists of the main body of pool water along with a spillover spa. Both Spa and pool share the same equipment and is the same body of water.

The problem I am experiencing is a surging of intermittent air coming out of the returns. When in "pool" mode it is barely noticeable, just a few air bubbles occasionally escaping from the returns closest to the equipment (shallow end).

But when in full spa mode (i.e. only spa returns are open) it is VERY noticeable. A few seconds of a steady water stream, followed by a few seconds of a blast of air bubbles.

There is no audible surge coming from the pump. It has a nice steady hum. Also note that if I hold my hand in front of a return jet, the outflow is the same steady flow throughout. There are no air bubbles in the pump basket. I have checked for pressure side air leaks to the best of my ability. I have also lubricated all o-rings at pump connections.

When I turn off the pump, I look to see if any water "spits" from any of the connections (i.e. pump basket, pump drain plug, connections where the PVC meets the pump housing, etc). Nothing. No spitting.

It is my understanding that air returning into the pool HAS to be a pressure side air leak. Am I wrong? Is there anything else I may be missing?

 

[Texas Splash]

Actually it's the other way around. If you have air in the system, it's getting "pulled" in - like sucking through a straw. So to rule-out a leak where air could be getting pulled-in, you investigate the suction side - from your skimmer(s) & main drain back to your pump. Pool School - Leak Detection. If you had a leak on the pressure side, you would have water getting pushed-out.

Now I will make this comment ..... I sometimes get the same thing you do in one jet, although I don't have a spa. Instead, I have a 3-way valve where I can divert water from my returns to a water feature. When I do that, there's a lot of sloshing and what I suspect to be some type of outgassing happening in that spot which seems to produce very small champagne-sized bubbles out of my closest return. They seem to flow intermittently as well about every 4 seconds or so. I don't lose any prime to the pump, and have exhausted numerous man-hours looking for a section side leak to no avail, so I just accept it when it happens. In your case, after you exhaust your suction-side for any leaks, you might find this occurrence to be somewhat typical for your system. Could you have a suction leak underground? .... maybe. It's not as common but does happen from time to time, but then that's a bit more difficult to troubleshoot and repair. So sometimes we have to pick & chose our battles. Maybe with the link I gave you it will help. In addition, some others who have a set-up like you may chime-in after me and give you other personal suggestions. Have a nice day.

 

[mikemass]

Oops. My bad. I was writing "pressure", but I did indeed mean "suction" side. As you can see from my check points. They are all suction side. I do fear an underground leak, but if that's the case I wouldn't even know where to begin. My entire surrounding area around the pool is a paver patio on top of a slab of concrete. Digging it up would be a near impossible task at this point.

 

[RobbieH]

Your SWG will create bubbles in the returns. To see if that's what is causing it, temporarily turn off your SWG and see if the bubbles go away.

 

[mikemass]

Your SWG will create bubbles in the returns. To see if that's what is causing it, temporarily turn off your SWG and see if the bubbles go away.

Yup. Attempted that too to no avail. As a matter of fact, I have my system set so the SWG doesn't operate when in Spa mode.

Here's my only other thought. I also have a blower motor for the spa. Which purpose is to inject air bubbles into the Spa when in use. But the blower broke last year and I never bothered replacing it, because I rarely used it anyway. It made the spa too violent for my liking. I don't know why this would matter, but it is a variable since last year. So I thought I'd mention it.

 

[Propbndr]

Are your skimmer levels constant at the minimum required level? If they fluctuate up and down, air can be sucked in as they are refilling. My pool will do the same thing if I let the level get too low. If your pool level is at or above the minimum, check the weir doors for sticking.

 

[WASP]

Have you tried bleeding any air that may have accumulated in the filter?

 

[mas985]

Here's my only other thought. I also have a blower motor for the spa. Which purpose is to inject air bubbles into the Spa when in use. But the blower broke last year and I never bothered replacing it, because I rarely used it anyway. It made the spa too violent for my liking. I don't know why this would matter, but it is a variable since last year. So I thought I'd mention it.

If air is coming out of the normal spa jets, that would be normal even without the blower. Many spas don't have or need blowers and can draw in air just fine without them. Blowers are necessary only for those spas where the venturi's cannot clear the air line by themselves. Have you removed the blower from the air pipe?

 

[mikemass]

Are your skimmer levels constant at the minimum required level? If they fluctuate up and down, air can be sucked in as they are refilling. My pool will do the same thing if I let the level get too low. If your pool level is at or above the minimum, check the weir doors for sticking.

I always run the water level 1/2 way to 3/4 to the mid-line of the skimmer gap. It's not sucking air and the doors are not sticking.

Have you tried bleeding any air that may have accumulated in the filter?

I always check this. Again not an issue whatsoever.

If air is coming out of the normal spa jets, that would be normal even without the blower. Many spas don't have or need blowers and can draw in air just fine without them. Blowers are necessary only for those spas where the venturi's cannot clear the air line by themselves. Have you removed the blower from the air pipe?

You may be onto something here. I have not tried this. But I can date the timing of this air surge to about the time that I noticed the blower was no longer working (mid season last summer). I am going to trouble shoot this when I get home tonight. If that seems to be the issue I will bite the bullet and spend the $200 to get a new blower.

 

[mas985]

Why is it an issue for you? If your spa works without blower, I would just leave it off. Save's on noise and electricity. If the bubbles really bother you, just put a temporary end cap on the air pipe.

 

[mikemass]

It's not that it bothers me per se. It's that I fear there is something wrong like a suction side underground leak. It didn't behave this way for 9-1/2 years. Now it is. Something has changed. As far as capping the air pipe, I haven't ruled that that is the culprit. If my tests determine it is, then yes that is a solution. But first I need to figure the cause.