big air bubble in pump basket

Frank in FL

Well-known member
Jul 3, 2019
224
Florida
What would cause a big air bubble in my pump basket? There is no bubble when pump is at 3400 rpms. But when the pump is at 2000 rpms after about an hour or two a huge bubble forms in the lid. It just recently started getting cooler here in Florida, but Ive never had this issue before.
I cant post a video, but here is a screen shot of it
 

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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Variable speed pumps often develop a small bit of air when on lower RPMs for a while which is why kicking them up in RPM once or twice a day helps to purge some air. But you state this just started happening. So the first reaction to air in the pump basket might be looking for any areas where air might get pulled-in on the suction side. Since your weather has been cooler, you might check the lid O-ring to ensure it's lubed well. Also make sure the water level in the pool is good and that the skimmer weir door is operating smoothly. As a last thought, make sure your cartridge filter hasn't gotten too dirty. When that happens, it can impede good water flow and cause a bit of a backlog in the pump basket. Happens to me every time.
 
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Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
15,745
Bedford, TX
Frank,

Pretty normal for there to be a small bubble or two a low RPMs.. If you have one at 2K, I would assume you have a very small suction side air leak. Most likely right at the pump lid O-Ring.. Lube it up and try it again..

There was also some discussion about the bubble being larger than normal is an indication about how dirty the filter is.. Not sure how true that is, but if it has been a while since you cleaned your filter, you might want to clean it and then report back if it had any effect the the size of the bubble.

Thanks,

Jim R.

Thanks,
 
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Frank in FL

Well-known member
Jul 3, 2019
224
Florida
Thanks fellas!
Ill check the filter tomorrow and goop up the lid seal. My filter psi has gone up by about 4 psi since it was cleaned about 2 months ago. Weir door is working as it should. Water level is good. not alot of debris in skimmer.
Ill report back with findings.
 

Frank in FL

Well-known member
Jul 3, 2019
224
Florida
Just now able to get around check out my lid. The lid oring was jellied up with lube and the air bubble was still present at low rpms but went away at a higher rpm. I took some food coloring and put it around the plastic clear window on the lid. Within a minute or so the food coloring was disappearing. So im 99% sure my culprit is where the window meets the plastic housing. It appears to be a friction fit and I dont think there is a seal there. How can I seal this up? Or do I need a new basket lid?
 

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Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
15,745
Bedford, TX
Frank,

I have a Pentair pump, but assume they are built in a similar way..

On mine, the O-Ring is under the clear lid, so even if the dye (or air) went through the gap between the clear lid and the handle, it still can't get in the pump.

Just based on what I have read here on TFP, it seems pretty normal to have bubbles at a low RPM.. As long as it goes away when the pump runs faster, I don't see it as much of an issue.

I have noticed that when my pump was new, the bubbles I had at low RPM were about the size of a nickle or a quarter, now more than five years, the bubble is more like the size of a dollar bill. It works fine, but I thought I'd "fix" the problem with a new lid and the cam-like locking ring... after I installed the new parts, I saw no difference at all.

Thanks,

Jim R.
 

IMissNimoy

Gold Supporter
Jul 3, 2018
67
SC
I have similar issues with the Hayward EcoStar on lower RPMs. The major difference is that mine look more like bees flying around in the pump basket. Higher RPMs will clear it up. I've changed the o-ring/lubed and it still happens at lower RPMs.