We've had a few people tell us that the bubbles we are seeing on the surface of our spa (none in the pool) when the pump is running is caused by a leak. We've done a bunch of investigating around the pump to test for a leak and either we are doing it wrong or it's worse than we think (underground), or these people are just crazy.

It only occurs when I have the pump on high speed and I vaguely remember growing up and having my Dad's spa do the same thing (no pool).

Does this sound (look) like a probable leak to any of ya'll?

Thanks in advance -
Laura

Check the lid of the pump basket for air leaks. Most of them need o-ring lube from time-to-time. This is by far the most common place for air to get in, and would explain the bubbles.

If you think it is a leak that would cause water loss, you can check for a leak via a bucket test.
pool-school/leak_detection

Thanks! Will do that!

Can I use just plain ole Loctite Clear Silicone in the tube or I also have on hand Blue Works industrial grade spray silicone.....will these suffice for an o-ring lube?

Thanks!
Laura

Silicone lube on a pump o-ring is great. The real key to this, though, is to get the o-ring AND the pump lid AND basket threads squeeky clean. Make sure the o-ring is not cracked, and reassemble, with the lubricant on the o-ring and the threads.

But I'm clueless here...are the things I listed above considered lubricant?? One is silicone sealant n a tube and the other is silicone lubricant in a spray can....are they the same as o-ring lubricant?

sealant (caulking) is certainly not the same thing. and the spray is also not correct.

You want a silicone or o-ring lube that is a gel in a tube ... like vasoline (but do not use vasoline as it is petroleum based)

It is more like a grease than a caulking.

Thank you! I didn't think they were the same thing, but wanted to make absolute sure.

Right, the stuff at Leslie's is what you want. They may have it in the pool section of WalMart or something like that too. It's VERY sticky and almost impossible to wash off.

Read your pump basket lid though, I've seen some that say "Do not use lubricant"

So, I got the o-rings all lubed up put back together and it didn't stop the bubbles. But then I started messing with the pool spa return valve for another reason and it just so happened that by adjusting it 100% open, the bubbles stopped! DO WHAT?? Can't figure out really why that would matter. And another thing....the bubbles only appeared when I had the pump running on high speed.

Could be that the valve is the source of your air leak. You can check by recreating the air leak and then running water over the valve, if the bubbles stop or greatly reduce then that's the source of your air leak. Normally they are on the suction side (before pump), but can happen on return side.

The reason it only happens on high is the pressure/water flow is then great enough to "pull" air in.

When you see the bubbles in the spa, do you notice air in the pump basket?

It may be that when you stop down the output and the pump is on high speed, that it (the pump) is cavitating.

If it is cavitating, you likely wouldn't see any air in the basket, however, after a short while, you should get air out of the filter pressure relief valve.

The solution? Open the spa return more or put return jets with larger openings on the spa returns.

Would cavitation cause that much air though?

With true cavitation you're never going to see any air at all unless you have a camera right at the vortex of the impeller. As soon as it passes the impeller tips the air will redissolve into the water and you'll never see it. Also if it was cavitation, your pump would sound like it was grinding gravel. Cavitation almost never happens in a residential pool pump.

Restricting the outlet would absolutely not cause cavitation, in fact that would prevent cavitation because it causes lower suction head, and very high suction head is required to create cavitation.

If you're not seeing any air in the pump basket then the leak is most likely between the basket and the impeller. Or there's air in the basket and you're just not seeing it.

Had some things come up that forced me to put this on the back burner and then we were out of town, so apologies for not getting back to you all sooner.

I am home now and I plan on taking your comments and checking things out more now that there are some other ideas as to what may be causing the bubbles.

I will be back in touch! Again, sorry for posting and then not checking back on my own thread!

Regards,
Laura

My guess it's coming from the air loop. Is there a nearby open venturi or blower?

Scott

I'm a real newbie to all this, so forgive me if I'm clueless on some of the tech terms....when you ask if I'm seeing air in the pump basket, I'm assuming you mean do I see air bubbles when I look down into it? I do know what that looks like because there were some air bubbles in there prior to me putting some lubricant on the o-ring, however since I did that I no longer see any bubbles in the basket (matter of fact if I didn't know better I would say there wasn't any water in there at all because when there are leaves in there I just see them spinning around you can't tell they are spinning in water at all due to the lack of air bubbles). I can still create the spa bubbles by slightly closing up the pool/spa return valve. Just did a water test and nowhere along the pipe or the valve did the bubbles decrease, but if I turn the return valve back to fully open, they stop...again only on high speed do they appear at all. Urgh!

If I feel around back there for air blowing out, I only feel air blowing from the fan on the pump itself.

Venturi or blower nearby....uhhh...nearby the spa bubbles or the pool equipmenet? Again, I'm just learning so forgive my ignorance.

A spa's blower is normally with the other pool equipment like the pump and filter, if it has one. A venturi is normally a vent just for letting air in and may or may not be closed all the way. It is usually by the seats.

Spa jets typically have two loops of pipe connected and feeding to them, an air loop on top and a water loop below it. Inside each jet is a small constriction. As water passes, it speeds up and creates a suction after the constriction. That suction draws air from the air loop. The air loop may be connected to either a venturi or a blower. Spa jets may generate enough vacuum to draw air from a blower line too if the distance isn't too great and the resistance is low. I think this is what is happening with your spa and is likely normal.

I haven't heard you fail the bucket test when checking for lost water.

Scott