Skimmer Suction Air Leak - Hypothetical?

[mas985]

On both the old and new lids, if I closely watch the water in the basket, I can see very, very small bubbles randomly coming up from the basket area and collecting under the lid. I estimate that I see one bubble every minute or so. It takes a long time, but the bubble under the lid gets slightly bigger..

That is exactly how outgassing behaves. It usually collects on the pump basket first down near the impeller inlet where the pressure is the lowest. Once the bubbles get large enough, they rise to the top.

I "assume" that when the pump is running at a low RPM, the suction that pulls the lid down is not as great as it would be at faster RPMs, so this is allowing a small amount of air to get into the basket area.

That can happen as well.

I also notice that as my filter gets dirty, the bubble under the lid gets a little bigger. Not much, but enough to notice.

That probably reduces flow rate so the bubbles are less likely to get sucked into the impeller inlet.

 

[JoyfulNoise]

@JoyfulNoise One last thing to try buy I'd pass on it in a heart beat is to swap the two pumps and see if the problem persists with the same pump at the new location or does the problem stay with the location where it initially began. I know it's confusing but can't writ it out any simpler.

I'd love to but my PB hard plumbed all the pumps, no unions . So swapping them is not a simple task sadly. Some day, when a pad rebuild or equipment upgrade is in my future, I'll add unions to all my pumps.

I know one definite source of an air leak is my suction cleaner. It uses the standard segmented hose lines and even though they stay mostly submerged, they do float and I am sure they are not airtight based on how cheaply they are made. But I have seen this phenomenon even with the cleaner line shut off at the 3-way valve so I think my pump lid probably leaks a little too. I've tried to lightly polish the plastic surface to smooth it out a bit because but seems very rough to me but that has not helped much. Granted it was only a very light polish and maybe I need to hit it a little harder.

I'm not as concerned about it as Pat is with his setup as I've learned to just accept it. I don't think its having any major impact on my pool hydraulics so it's not huge deal.

 

[JoyfulNoise]

This is exactly how my old IntelliFlo works...

I believe that air is actually coming in around the lid O-Ring.. I even bought a new lid assembly, including the clear lid, the locking ring that holds the lid, and a new O-Ring. Used plenty of pool lube.. It made zero difference.

On both the old and new lids, if I closely watch the water in the basket, I can see very, very small bubbles randomly coming up from the basket area and collecting under the lid. I estimate that I see one bubble every minute or so. It takes a long time, but the bubble under the lid gets slightly bigger..

I "assume" that when the pump is running at a low RPM, the suction that pulls the lid down is not as great as it would be at faster RPMs, so this is allowing a small amount of air to get into the basket area.

I also notice that as my filter gets dirty, the bubble under the lid gets a little bigger. Not much, but enough to notice.

I consider this normal operation and just ramp my pump speed up once a day to keep the air under the lid in-check..

I guess I could use epoxy and glue the lid in place, to check my theory, but suspect that might be an issue the next time I tried to clean the pump basket.

Thanks,

Jim R.

I will say that I HATE the Pentair lid designs. The way they have it set up with the clear plastic part holding the o-ring and the separate locking ring setup makes it annoying to get the pieces to all sit and mate correctly. And I bet that the design contributes a lot to the lid not mating and sealing properly. I watched my PB do some work early on with my setup and noticed that he used a rubber mallet to "hammer" the lid locking-ring closed. I asked him if that was bad for it and he said that was the only way to get a solid seal with the Pentair design, hand-tightening rarely works. He quipped, "If you hit it too hard and break the ring, just buy a new one ..."

 

[Jimrahbe]

I watched my PB do some work early on with my setup and noticed that he used a rubber mallet to "hammer" the lid locking-ring closed.

Matt,

I too use a rubber mallet... I do give it a little nudge to tighten or loosen the lid, but not quite a "hammering"..

I recently when for a "ride-along" with a local pool guy who does routine weekly maintenance and chemicals... He used a metal tool (basically a pipe) to whack all of his pump lids open and closed. Huge dents in all of them...

I plan to write a review of my experience...

Thanks,

Jim R.

 

[JoyfulNoise]

Matt,

I too use a rubber mallet... I do give it a little nudge to tighten or loosen the lid, but not quite a "hammering"..

I recently when for a "ride-along" with a local pool guy who does routine weekly maintenance and chemicals... He used a metal tool (basically a pipe) to whack all of his pump lids open and closed. Huge dents in all of them...

I plan to write a review of my experience...

Thanks,

Jim R.

That sounds like an excellent thread ... can't wait for the read.

Was it like an episode of that reality TV show "COPS" where you run down errant pool store employees and throw a night-stick at the back of their legs to knock them down?

 

[wireform]

It's one thing if the lip on the cover breaks, just spend for a new but I've seen the pump portion of it cracked and can guarantee it was from over tightening and that's another story to rectify. My opinion, I have the least air leakage troubles from the pentair style covers then from the hayward square kind with the two swinging hold downs.

 

[Texas Splash]

It just started to rain here, so I can't do much outside today, but I'm going to set the stage for what's about to happen tomorrow.
In this first thumbnail pic, you see the basic concept of my suction line. The red line (original flex pipe) against the pool is what I cut and bypassed in August. It was pulling down and away from the skimmer about to break. The red line by our black dog (Buccee) is the last bit of remaining flex line on the suction side. I only cut & replaced what you see in yellow. After that work, I did a pressure test with my new manifold and it held water pressure at about 17 psi for about an hour while I inspected all joints for leaks.



This thumbnail simply shows the tail end of the suction line coming back to the pad. This is how it looks today after my pad re-do a few days ago. The pump, check valve, and 2-way are all new. I can re-measure, but it's about 45 ft from the skimmer to the pump with what I believe are about 8ea 90 degree elbows along the way.



Here are my two pumps. The Waterway Supreme on the left has worked great for about 10 years. I've taken it apart more than once to clean it up, give it a new shaft seal, etc. It always runs on low speed. Since day 1, it's always had a tiny bit of air under the lid, but nothing substantial, and nothing like a large gap of an inch or two until this season.

The pump on the right is my new Power Flo Matrix. I got it a couple years ago as a back up since it appeared to be identical to the Waterway. Just a couple cosmetic differences, but as I look closer at the HP ratings, I believe the Power Flo may be slightly weaker.



Tomorrow I will perform two types of water pressure tests using two different products I made. One is a simple staff design, the other a true manifold like you would buy online. The reason I'm doing both is because the staff tester screws into the skimmer port while the manifold has a blow-thru plug at the end and inserts a tiny bit more into the skimmer hole. I want to see if there's any difference at the entrance of the skimmer hole I could not ID during my static water dye test.




I have two theories:
1 - I have an air leak that was misdiagnosed or developed after successfully completing pressure testing in Sept.
2 - Both of these pumps are showing signs that they are not capable of pulling water adequately based on my pool configuration.

As an example, the Waterway shows much less air under the lid than the Power Flo, but it was still there. Why? Look at this pic below. As a test, I placed the Waterway pump right next to the pool and did not glue any fittings. It ran for 24 hrs absolutely air-free in the pot. Hummed as if it was off the showroom flow. But it only had a few feet of line and no filter restriction.


So why does this Waterway get air under the lid at 45ft away at the pad? Suction line leak? - maybe. But if it passes testing tomorrow, I can only assume the pump is showing signs of wear/age and perhaps not pulling as strong as when it was new in 2013. That might also explain why the new Power Flo Matrix is showing MORE air than the Waterway ever did because it appears to be a slightly weaker pump. Only later did I learn that both of these pumps are technically rated for AGP use. Yet another reason why I'm wondering if the pump(s) are showing signs that they are starving for water as opposed to an air leak. My system was originally installed with a check valve, and I suspect that's why they did it since these technically aren't self-priming pumps. I honestly never had a problem with the Waterway before, but now I am wondering if these pumps are struggling with the distance to pull the water.

I'll report back tomorrow after my pressure testing to see.

 

[mas985]

Just to clarify, you said you get air with both pumps but is it also at both speeds? Do the pumps fully prime at full speed and completely purge all the air? If there is too much head loss in the plumbing, this would show up on high speed and the pumps would not fully prime.

 

[Texas Splash]

Just to clarify, you said you get air with both pumps but is it also at both speeds? Do the pumps fully prime at full speed and completely purge all the air?

The Waterway has always primed quickly on high, purged all air, then I'd go to low speed in under 30 seconds. Up until this year it had very little air under the lid. When I decided to swap it out a week ago, the water level would drop maybe one inch and stay there.

The Power Flo is much different. It takes much longer to fully prime and purge all the air. It churns in the pot for a good 2 minutes or so before reaching 100% full of water to where I am comfortable switching to low. Once on low speed, the water level falls much faster. Only takes about an hour to look like it does in the video clip earlier, down by about 2-3 inches. It seems to hold there, but it's uncomfortably low in the pot.

 

[JoyfulNoise]

I thought AGP pumps couldn’t be used on inground pools because they are not self-priming?

 

[mas985]

Some AG pumps are self-priming and the Matrix is one of them.

If there was an air leak in the pipes or fittings or valves, then it should leak more at high speed than low speed. The only thing that I have seen that leaks more on low speed is the pump lid for certain pump designs.

 

[Texas Splash]

I thought AGP pumps couldn’t be used on inground pools because they are not self-priming?

Years after our install, that's what had me curious. But I "think" the installation of the check valve was on purpose to help keep the pump well primed just in case. Perhaps not ideal, but it's always worked well for 10 years.

 

[JoyfulNoise]

The solution is simple … you need a bronze body 5HP commercial grade pump like the CMK-50

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/commercial/pumps/c-series/c-series-commercial-bronze-pool-pump-brochure.pdf

You can easily achieve 200-300GPM that no air bubble would ever survive in …

Your return jets will flow like Niagara Falls

 

[bdavis466]

I will say that I HATE the Pentair lid designs. The way they have it set up with the clear plastic part holding the o-ring and the separate locking ring setup makes it annoying to get the pieces to all sit and mate correctly. And I bet that the design contributes a lot to the lid not mating and sealing properly. I watched my PB do some work early on with my setup and noticed that he used a rubber mallet to "hammer" the lid locking-ring closed. I asked him if that was bad for it and he said that was the only way to get a solid seal with the Pentair design, hand-tightening rarely works. He quipped, "If you hit it too hard and break the ring, just buy a new one ..."

The XF’s lids are even worse… they are the same design as the whisperflo/Intelliflo, but they have a stop in it that limits how tight you can get the lid (the ears can’t go past 180 degrees). They never seem to tighten down enough and in my experience, the XF pumps always have more air in the baskets than the others. They are great pumps but terrible lids.

On low speed it’s not uncommon to have the water level 2” below the lid.

Every XF that I’ve ever used as a water feature pump has never had a single bubble in it.

 

[mas985]

One more follow up.

When running on high speed and after the pump is fully primed, do you still see small bubbles passing by in the pump basket? They may not accumulate and pass through to the filter but they may still be there.

Another way to test this is if you run on high speed for some time, does the filter accumulate air?

If so, the air leak is still there on high speed and could be anywhere in the suction plumbing.

 

[Texas Splash]

after the pump is fully primed, do you still small bubbles passing by in the pump basket?

Yes - very tiny ones.

Another way to test this is if you run on high speed for some time, does the filter accumulate air?

I'll check that in the morning. I usually don't run on high longer than to prime, but I'll give it a shot.

 

[Texas Splash]

Doing my pressure testing today and seeing a little inconsistency.

Question, what is a good psi for water testing? I saw on one site they said not too high, only go to about 15-17 psi for water. Any thoughts?

 

[mas985]

Normally, you want to test slightly above maximum pressure that the pump/plumbing system would see in operation. If you don't see more than 20 PSI in filter pressure, 20 PSI is sufficient. But that is for new plumbing to test the pipe weld strength.

For older plumbing, almost anything is going to reveal a decent size leak. The pressure should drop fairly quickly if there is a leak. The higher the initial pressure, the faster and the more noticable the drop. But I probably wouldn't go much above 30 PSI. Technically, you could go as high as the lowest rating in the equipment but that is overkill.

One thing to be aware of is that the water pressure in the "sealed" plumbing is going to have some dependency on the air temperature and sun exposure. As air temperature rises or the sun hits the plumbing, some of that energy transfers to the water and the pressure will increase and visa versa. So when comparing temperatures it is a good idea to get a reading at the same time of day. Early morning is best before the sun hits the plumbing and air temperature rise. You can usually get a good idea of the range by getting a reading early morning and monitoring over the course of the day. But like I said before, if there is a leak, it should drop pretty quickly unless it is very small.

 

[mas985]

One more thought that I had mentioned in a previous post. Pump basket lids aren't really made to seal well under pressure so that may leak if it is part of the measurement.

 

[JamesW]

One more thought that I had mentioned in a previous post. Pump basket lids aren't really made to seal well under pressure so that may leak if it is part of the measurement.

Would a vacuum test be a good idea if they have a vacuum pump?