Bubbles Returning To Pool And Cavitating Kreepy Krauly

[TryingToBeMyOwnPoolGuy]

Hi folks -

I am new on this forum, and I am sure this problem has been answered before. Having read some other answers, I am thinking about disassembling my pump, but it is in a difficult location and I want to hear what you say before I start. I've had this problem for months, so I hope you can help!

Here's my info:

15kgal in-ground pool.

passive solar water heater on my roof.

PacFab WFE-3 3/4 HP pump (looks to be the same as Pentair)

Hayward 3600 DE filter

For the last 4.5 years, the system has worked well.

This may be a red herring, BUT, I cleaned the Hayward filter one day (removing all of the old DE, cleaning it out, re-siliconing the gaskets, replacing the pressure gauge on the top, and recharging it). The problems seemed to start after that (or perhaps I did this because of the problem - now I can't remember).

However, this seems like it can't be the problem, since it is on the positive pressure side.

The symptoms:

-air coming into pool from returns (more from one than the other)

-cavitating pump, kreepy krauly

-air under the pump cover. To be clear, it is full to just under the top, but there is air in the top.

-kreepy krauly not working well at all

-pressure at the filter varying between 8-12 due to cavitation (when the solar is on, see below).

Usually it was up around 15-20 before this, and steady.

-releasing the air valve bleeder on the top of the Hayward always releases some air, even though I have just bled it out. I don't know if this is typical or not.

What I have done:

1. Using my home warranty I called a pool repair guy. He seemed very professional.

They took apart the return pipes coming out of the ground and into my pump and resealed all of the joints.

The problem persisted (i.e., there was low pressure), but the guy said I needed a bigger pump for my system.

He seemed to not take into account that I told him the pump and kreepy krauly had worked just fine for 4.5 years before this, so I didn't understand why I suddenly needed a bigger pump. The pump has been replaced within the last few years.

So then he said he thought that air was coming in via my kreepy krauly tubes.

2. I tried disconnecting the kreepy krauly, and the bubbles persist, but the cavitating stops. The pressure remains steady at around 13 when the solar is not engaged, it goes up to a steady 19 or so when the solar is circulating.

3. With the kreepy krauly connected, the cavitating comes back, and the pressure varies between 5&7 without the solar engaged, when I turn on the solar manually, initially the pressure goes up to around 15-17, then drops to 8-12. The bubbles are still there whether the solar is on or not.

4. I've checked all the hoses on the Kreepy Krauly and they aren't plugged - neither is the Kreepy Krauly for that matter.

5. I carefully cleaned the pump cover and re-greased the pump cover gasket with silicone. This seemed to help for a short while. Then I read in some forum that my pump might have a lot of debris in the vanes. So when I removed the pump cover to feel around inside, there was a definite vacuum release hiss, so I think that is sealing well. But I didn't feel anything in the vanes.

So, could all of this just mean I need new tubes on my kreepy krauly? Or could there be debris I can't feel in my pump vanes? Or could there be an air leak under ground? Or in the solar (but I think that is on the positive side...?). Or all of the above?

Thanks for any insight you can give!

[txpoolguy]

First off, based on your description, a bigger pump and new hoses for the Kreepy will not likely fix your problem. It sounds to me as though you have one of the following:

1. A vacuum leak on the suction side of your pump - most likely above ground. Replace the pump lid gasket first.

2. The Kreepy may have picked up some debris that is now lodged in one of your pipes, causing a restriction to flow.

3. Debris may be lodged in the impeller of your pump.

Since the filter is on the pressure side of the pump, it's not likely part of the problem, although it may have made the problem more visible, since cleaning the filter allows the water to flow more easily.

The bubbles coming into the pool, air in the pump lid, and lower pressure on the filter, all would be consistent with one of these problems. Cleaning the filter may be coincidental. The pressure rise during solar operation sounds normal, as the pump is pushing water thru the solar fixture - increased resistance to flow.

All of these issues can be difficult to locate & correct. I'd recommend a very experienced technician to diagnose. The guy who was already there didn't know what he was looking at and was trying to upsell you - typical for the home warranty companies that I've dealt with.

[Mark]

It is very unlikely that you have cavitation since cavitation bubbles do not make it past the impeller. As txpoolguy suggested, it is more likely to be an air leak in the suction side of the plumbing. Because the filter pressure drops so much with the cleaner engaged, my guess is that there is a blockage in the cleaner and/or cleaner line.

[TryingToBeMyOwnPoolGuy]

Dear txpoolguy -

Thanks for the reply! As I said, the professional did a good job (I think) of re-sealing all the suction-side above ground joints, there was a satisfying vacuum release sound when I took the cover off the pump, and I checked the Kreepy hoses for debris and they are clear. So that leaves pump impeller debris on your list. I didn't feel any from the pump filter side, but I understand that it may not be reachable from there. I'll try taking it apart next weekend.

Thanks!

First off, based on your description, a bigger pump and new hoses for the Kreepy will not likely fix your problem. It sounds to me as though you have one of the following:

1. A vacuum leak on the suction side of your pump - most likely above ground. Replace the pump lid gasket first.

2. The Kreepy may have picked up some debris that is now lodged in one of your pipes, causing a restriction to flow.

3. Debris may be lodged in the impeller of your pump.

Since the filter is on the pressure side of the pump, it's not likely part of the problem, although it may have made the problem more visible, since cleaning the filter allows the water to flow more easily.

The bubbles coming into the pool, air in the pump lid, and lower pressure on the filter, all would be consistent with one of these problems. Cleaning the filter may be coincidental. The pressure rise during solar operation sounds normal, as the pump is pushing water thru the solar fixture - increased resistance to flow.

All of these issues can be difficult to locate & correct. I'd recommend a very experienced technician to diagnose. The guy who was already there didn't know what he was looking at and was trying to upsell you - typical for the home warranty companies that I've dealt with.

[TryingToBeMyOwnPoolGuy]

Dear Mark -

I may not be using the terminology correctly. By "cavitation," what I mean is the oscillation in the pump pressure, which makes the Kreepy Krauly hoses oscillate on the pool surface like an unseen hand is grabbing them. What is the proper term for that?

Also, as I said, I checked all the K-K hoses and they are clear.

-gary

It is very unlikely that you have cavitation since cavitation bubbles do not make it past the impeller. As txpoolguy suggested, it is more likely to be an air leak in the suction side of the plumbing. Because the filter pressure drops so much with the cleaner engaged, my guess is that there is a blockage in the cleaner and/or cleaner line.

[Mark]

"Oscillation in pump pressure" works for me.

Anyway the reason is oscillates is probably because you are getting a lot of air into the suction so the pump is going through priming cycles.

Try repeating #2 you listed in your first post but this time wait and see if the bubbles ever completely disappear from the returns. Also, check the pump basket and see if the pump fully primes. If the cleaner hose is allowing air into the system, it could just be that you didn't allow enough time for all of the air to purge out of the filter.

[TryingToBeMyOwnPoolGuy]

Great idea, Mark, will do! Any suggestion of how long I should wait? 5 minutes? A half hour?

Yeah, sorry I wasn't clear in my original post. When I gave ranges for the pump pressure, I meant that it was oscillating between those two values.

-gary

"Oscillation in pump pressure" works for me.

Anyway the reason is oscillates is probably because you are getting a lot of air into the suction so the pump is going through priming cycles.

Try repeating #2 you listed in your first post but this time wait and see if the bubbles ever completely disappear from the returns. Also, check the pump basket and see if the pump fully primes. If the cleaner hose is allowing air into the system, it could just be that you didn't allow enough time for all of the air to purge out of the filter.

[Mark]

The pump basket should be first to purge the air. Normally a pump will purge all the air in less than 5 minutes. The filter may take longer unless you have air bleeder valve near the top of the filter. This will allow you to remove all of the air in a few seconds with the pump running.

[TryingToBeMyOwnPoolGuy]

Ok, I took the pump apart and here is what the shaft looks like.

http://cseweb.ucsd.edu/~gary/DSCN0058.jpg

other pictures, including the

http://cseweb.ucsd.edu/~gary/DSCN0057.jpg

http://cseweb.ucsd.edu/~gary/DSCN0056.jpg

I am guessing that the air came in here, as I am guessing that this is not sealing properly with this kind of corrosion. Do I need a new pump?

The pump basket should be first to purge the air. Normally a pump will purge all the air in less than 5 minutes. The filter may take longer unless you have air bleeder valve near the top of the filter. This will allow you to remove all of the air in a few seconds with the pump running.

[TryingToBeMyOwnPoolGuy]

By the way, this pump was supposed to have been replaced a a year and a half ago. Do these pictures look like a 1.5 year-old pump??

Here is the link again for your convenience...

http://cseweb.ucsd.edu/~gary/DSCN0056.jpg

[Mark]

The motor shaft is located on the pressure side of the pump so air cannot be sucked in from there. A bad shaft seal will leak water out not air in. Air will only enter into a plumbing system on the suction side of the pump which includes the pump basket lid seal, drain plug or any of the suction side plumbing.

As for the age of the pump, it does look a bit older than 1.5 years but if the seal is good (i.e does not leak water) and it does not have any bearing noise, I would say leave it alone.

But again, your air leak is probably on the suction side of the pump so I would focus there.

[TryingToBeMyOwnPoolGuy]

Hi folks -

I have now taken the pump apart to check for things clogging the impeller - nope, everything was fine inside. I put it back together (replacing the pump seal), I also, on the advice of the guy at Leslie's, who said he had seen leaks in the filter cause bubbles - not sure how since this is the positive side of the pump, but what the heck, it is easy to do, I took the cover off the filter and put it back on making sure the giant O-ring was in place, and everything worked fine for a little while (I dunno, maybe 10-20 minutes??), but now it is back to cavitating (pump pressure running between 11 and 14 or so) and the kreepy krauly is sitting on the bottom of the pool doing nothing.

After all that work, I performed the experiment Mark suggested. If I disconnect the Kreepy Krauly, the pump pressure returns to a nice steady value of 20, and *almost* all (but not *quite* all) of the bubbles disappear from the returns in about five minutes or so. There are no more bubbles in the pump filter window, no sounds of a struggling pump, etc.

Again, there are no obstructions in the Kreepy Krauly (KK) tube, and if I plug in the KK again, it starts to work for a couple of minutes before the cavitation starts again. The bubbles return in full force, and the pump pressure oscillates between 10 and 14 pounds.

At this point, my hypothesis is that the KK puts a bigger load on the pump, and causes it to suck in more air from some underground crack in the return pipe. Any other (cheaper?) ideas? If I want this checked out, what to I ask the pool guy to do? Is it called "camera the pipe"?

Great idea, Mark, will do! Any suggestion of how long I should wait? 5 minutes? A half hour?

Yeah, sorry I wasn't clear in my original post. When I gave ranges for the pump pressure, I meant that it was oscillating between those two values.

-gary

"Oscillation in pump pressure" works for me.

Anyway the reason is oscillates is probably because you are getting a lot of air into the suction so the pump is going through priming cycles.

Try repeating #2 you listed in your first post but this time wait and see if the bubbles ever completely disappear from the returns. Also, check the pump basket and see if the pump fully primes. If the cleaner hose is allowing air into the system, it could just be that you didn't allow enough time for all of the air to purge out of the filter.

[Mark]

Yes, a filter can cause air to enter the system but only when the pump is off. With the pump off, the water in the filter creates a slight negative pressure which can draw in air from the backwash valve and/or other areas which will seal on positive pressure but open up on negative pressure. So it is possible but if you see air in the pump basket, then it has to be a suction side leak.

Also, the cleaner will increase the suction side head loss which in turn increases the suction at the pump and associated plumbing. With the larger negative pressure, things that did not leak air before will start to draw in air. Assuming there is not any extra blockage in the cleaner which is causing higher than normal head loss, the usual suspects for air leaks in order of likelyhood:

Pump lid gasket

Pump drain plugs

Valves with o-ring seals

Cracked pipe

Lube the lid gasket and drain plugs to see if that helps. If not, then use a hose over the valves and plumbing to see if the air disappears at some point but you need to be patient and look for the air to reduce in size. A broken pipe is always a possibility but I would definitely rule out everything else before going down that road.

[TryingToBeMyOwnPoolGuy]

Thanks, I have tried all those things (except the broken pipe) once, but I will try them again, as you suggest. I saw somewhere that shaving cream on the pipe fittings was a good way to tell...

The main thing I probably have not done correctly in testing the pipes is using the hose to stop the leaks. How do you know you have "enough" water on the pipe fittings? Seems like using the hose is a tricky way to stop a leak.

By the way, I don't believe I have any valves with o-rings on the suction side. There is just a pipe coming out of the ground and going directly into the pump.

cheers,

gary

Yes, a filter can cause air to enter the system but only when the pump is off. With the pump off, the water in the filter creates a slight negative pressure which can draw in air from the backwash valve and/or other areas which will seal on positive pressure but open up on negative pressure. So it is possible but if you see air in the pump basket, then it has to be a suction side leak.

Also, the cleaner will increase the suction side head loss which in turn increases the suction at the pump and associated plumbing. With the larger negative pressure, things that did not leak air before will start to draw in air. Assuming there is not any extra blockage in the cleaner which is causing higher than normal head loss, the usual suspects for air leaks in order of likelyhood:

Pump lid gasket

Pump drain plugs

Valves with o-ring seals

Cracked pipe

Lube the lid gasket and drain plugs to see if that helps. If not, then use a hose over the valves and plumbing to see if the air disappears at some point but you need to be patient and look for the air to reduce in size. A broken pipe is always a possibility but I would definitely rule out everything else before going down that road.

[Mark]

Looking back at your first post, you mentioned that without solar, the pressure was around 13 PSI and then drops to about 6 PSI with the cleaner. This seems like a bigger drop than it should be. My suction cleaner drops the pressure by only 1 PSI or so. If the bypass valve in the cleaner is stuck or plugged in someway it may be creating too much suction.

Also, inspect the pump lid gasket itself. If it is cracked or damaged in anyway, it may need to be replaced. But my first guess is that there is something wrong with the cleaner.

[TryingToBeMyOwnPoolGuy]

Do you mean the spring-loaded in-line valve where it connects into the skimmer? I think it is ok, but I will check.

Looking back at your first post, you mentioned that without solar, the pressure was around 13 PSI and then drops to about 6 PSI with the cleaner. This seems like a bigger drop than it should be. My suction cleaner drops the pressure by only 1 PSI or so. If the bypass valve in the cleaner is stuck or plugged in someway it may be creating too much suction.

Also, inspect the pump lid gasket itself. If it is cracked or damaged in anyway, it may need to be replaced. But my first guess is that there is something wrong with the cleaner.

[thecanuck22]

I had your exact same problem. I at first thought it was my KK and did everything possible to eliminate that part of the problem.

I spoke to several pool people in my area and was given the following advice which worked for me last season.

First get a flashlight and look into the basket with it running, can you actually see bubbles entering the basket? If so the problem is more than likely the union between the pump basket and the piping. They asked me if i had ever fired up my pump dry, of course i had, and they explained that doing that causes alot of force on that fitting, causing that union to 'shrink' ( i dont know if thats an accurate word to use). I could see air entering, so, and dont laugh, i used some plumbers epoxy ( i wouldnt reccomend that now) on all the connections i could see on the suction side of the basket. THe union the elbows, everywhere there was a connection.

I also took out all my drain plugs on the basket, used 5 wraps of teflon tape and re-inserted them tightly.

Took out my lids gasket, cleaned it really good and applied some sort of sealant, almost like vaseline but not vaseline, that i had around for some of the motorized toys o-rings for the pool.

Last season I had no bubbles, Kreepy worked great and keeping the pool clean was again very easy.

HTH

[TryingToBeMyOwnPoolGuy]

After about a year of having this problem, and having three pool guys come out, I finally figured it out.

The last guy who came out showed me the rubber ball test. This is a test where you stop up the pipe with a ball (I used a tennis ball) at the suction side. If the ball comes up after a while, then the leak is below that point, as bubbles have come up and the ball comes free. If the ball stays without coming loose, then the pipe is good below that point. So, for example, at the bottom of the skimmer, you can remove everything so just the pipe hole is there, and put in the ball with the pump running, it should stay there. If it doesn't (pops up after a few minutes), then there is a leak in the pipe below that point.

So, I tried doing this with the skimmer basket in, and it popped up. So I had a leak somewhere IN the skimmer housing. So I connected the Kreepy Krauly directly to the pipe, taking out the whole skimmer basket setup, and voila! problem solved, one year (at least) into having it....Now I have to clean the pump basket more often is all.

Do you mean the spring-loaded in-line valve where it connects into the skimmer? I think it is ok, but I will check.

Looking back at your first post, you mentioned that without solar, the pressure was around 13 PSI and then drops to about 6 PSI with the cleaner. This seems like a bigger drop than it should be. My suction cleaner drops the pressure by only 1 PSI or so. If the bypass valve in the cleaner is stuck or plugged in someway it may be creating too much suction.

Also, inspect the pump lid gasket itself. If it is cracked or damaged in anyway, it may need to be replaced. But my first guess is that there is something wrong with the cleaner.