Help with pressure side (probably) leak

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T

tphaggerty

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LifeTime Supporter
Jun 27, 2007
229
Poughquag, NY
Our pool definitely has a leak, starting about 8 weeks ago or so. Much larger water loss than normal. I have been letting it go to try and get a feel for when the leak is. IG pool, BTW. I did several bucket tests and am confident that I do have a leak.

Initially, I thought it was in one of the skimmer boxes (because we seemed to lose water quickly until the level reached the bottom of the skimmers). But, once the water was below the skimmers, I taped the fronts and filled them up - they have been holding water steady for at least a week - so no leak.

I did a quick dye test around the returns, stairs and fiber optic light ports, and checked the liner as much as possible (no obvious tears or holes, no soft spots) - so, no obvious leaks. Now the water level is just at the top of the returns. And, I notice that the return in the deep end is now blowing lots of bubbles. Turn off the solar and SWG to make sure they are the cause and they aren't. And, the water level seems to have stabilized. I also put a fitting in the return to make sure that the air for the bubbles wasn't being drawn in right at the return, and used some butyl tape around the fitting on the pool side to prevent any air leaks there - still bubbling vigorously! (I did check the filter and all to make sure that the air wasn't being pulled in on the suction side, no air in the pump basket, no air in the filter, no bubbles in the shallow end return).

I am planning on pressure testing both of the returns (have to disassemble quite a bit of plumbing, so I haven't done it yet). It seems a reasonable conclusion that there is a leak in the deep end return line that is currently acting like a venturi and pulling in air. The lines are all flex PVC and I'm relatively certain that it is one piece from the filter side return all the way to the wall return fitting. I just can't visualize how a pressure side leak could be introducing air. Anyone have any ideas?
 
As the water level drops, the pump will have a harder time lifting the water, and could introduce some bubbles. Have you done a 24hour test comparing the water loss with the pump on and pump off? Have you checked your waste line for leakage while the filter is running?
 
No, the pump isn't introducing bubbles. If it was, the filter would have air at the top and I have checked that. Plus, then I would be getting bubbles from both returns. Also, I don't have a dedicated waste line, I attach a line when I backwash. No signficant leakage from around the pump, filter or anywhere on the equipment pad.
 
tphaggerty said:
No, the pump isn't introducing bubbles. If it was, the filter would have air at the top and I have checked that. Plus, then I would be getting bubbles from both returns. Also, I don't have a dedicated waste line, I attach a line when I backwash. No signficant leakage from around the pump, filter or anywhere on the equipment pad.
Click to expand...

The pump is the only source of bubbles in a system. Either due to insufficient water intake or an air leak. It doesn't always accumulate in the filter. The return that is closest to the pump is the first to show bubbles, and it's common to only get them in one return.
 
JohnT said:
The pump is the only source of bubbles in a system.
Click to expand...

Weird, I replied to this earlier but it isn't showing up.

Anyway, the PUMP IS NOT CAUSING THE BUBBLES!!!! (see below). I think you need to be careful about making blanket statements like this. Just as an example, a faulty or misplaced vacuum relief valve on solar will introduce bubbles in the return and it is clearly (1) not the pump, and (2) on the pressure side (after the pump). There are WAY too many variables in pools to be able to say this in such a categorical manner.

Now, to return to my problem. I was able to pressure test the returns today, and sure enough, the deep end return has a leak. Don't know where, but it will not hold pressure. The other return holds pressure very well (shot the test plug about 15 feet in the air - if you ever do this, DO NOT put your face in front of the test plug!!!). I sealed the deep end return at my equipment pad and at the pool. Upon restart, no more bubbles. I am adding water to the pool to make sure that this is where the leak is.

I believe that the flex PVC has worked loose at the pool return fitting. The line is one piece of flex all the way from the equipment pad to that fitting, so unless the line has been crushed (doubt it as the pool has been running for 3 seasons) or punctured somehow, this is the only thing that makes sense. The lines were blown and filled with antifreeze, but maybe the area around the fitting froze enough to loosen the connection. It still is not clear why air is getting in the line, but maybe the leak is somehow acting like a venturi line. Anyone else ever have anything like this happen?

Unfortunately, there is a 10 foot concrete deck behind this return. I have to think about how to resolve this as I don't want to operate with only one return.
 
TP, pressure test that line - it'll resolve the question as to the soundness of that line :) I saw this last night and agreed with John's assessment - albeit, I don't know 'Jack' about solar systems - his 'blanket statement' is good for probably well over 98% of 'bubbling' returns, if someone has a system wherein the other ~2% may come into play we'd need to know about it and the possibility that it would come into play. :handshake: However, a leak that that both let's water out and air in is IMO an extraordinary thing, the one thing I've seen is a return leak that lowers the water while the pump is off and after a little while of the pump being on, the leaked water has drained from that area and air can then be entrained into the pipe - you've gotta have DRY soil for that.

We're all trying to give the best advice we can ... sometimes we make an unwarranted assumption or neglect/ forget a possibility, but with feedback like you give we can modify what we've said (and this sometimes helps someone 'searching' a similar problem, it's all good!)
 
Yeah, I know John wasn't trying to steer me wrong, but I've done enough work on and around my pool to recognize a suction leak. Wasn't trying to sound harsh, but I've been working on this leak for a while and did a lot of work before putting in the first post. Anyway............

I did pressure test as per my post just above yours. And, yes, it is leaking. And I agree, it is very hard to imagine what is happening, that is why I did not suspect this line in the first place (and why I asked for help on the board). As of right now, I have that line blocked (at both the pool and the filter) and am checking further to make sure that is really where the leak is. The bubbles were very noticeable and only from that one line, there are no bubbles now that the line is blocked off. As for dry soil, we have that. But, there is also a fair amount of gravel backfill around the pool and that could be where the water is going. I haven't found any wet spots or anything outside of the pool that would indicate a leak. A true mystery.

I can think of 2 ways this might be happening. First, the leak is actually a split and the water is entering a "chamber" excavated by the water, mixing with air being drawn in and then continuing on to the pool (sort of like having my 2" line go into a 6" or 8" chamber open to air). Second, if there was an obstruction, like a piece of gravel or rebar protruding into the flex PVC, it might act sort of like a flapper valve, closed when under water pressure except a bit of air being drawn in by the pressure reduction just past the obstruction - but when there isn't water pressure, it floats open and lets the leaking begin. Pure speculation, I know. I hate the thought of ripping up lots of concrete to find out the truth.
 
In flex pipe, at least in theory, it is possible for a venturi jet to get created by a puncture. That would cause it to draw in air when water was flowing but leak when the pump was off. There would need to be a little flap of pipe, or whatever caused the puncture, pushed up into the stream on the pump side of the hole in just the right way without the hole being completely blocked. It seems incredibly unlikely that this could happen to me. Creating a venturi jet is difficult enough when you are trying to do it, I can't really imagine it happening at random, but you never know.
 
I really don't understand it myself. Given an unlimited budget (and patience) I would tear up the concrete just to find out what is happening! In the words of former Pres. Bush - "ain't gonna happen".

If it proves out that this line has the leak, I'm not sure what I'm going to do. I wonder how much it would cost to get a rotor router type guy out with a fiber optic camera setup to check the line out. If the leak is at the pool wall fitting, I could see cutting out a small section of concrete to do the repair. Otherwise, I think my options are to put in a new return on the side where I only have a 3 ft concrete slab to deal with, or to possibly use a 3 way valve to turn my main drain into a drain/return as needed (I could do that at the equipment pad - anyone do anything like that before??).
 
TP,

I've been watching this thread and trying to figure out how that pressured line can allow air in the pool. I am really skeptical that is the problem. I've reread all you've done and it makes good sense but it simply doesn't seem to me that you could create enough of a venturi to overcome the pressure generated by the pump.

I wish I could suggest something positive but I'd sure be reluctant to break up concrete based on the info obtained so far. Do you think it's worth repeating the pressure test to confirm your results or would that simply be a waste of time?
 

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duraleigh said:
Do you think it's worth repeating the pressure test to confirm your results or would that simply be a waste of time?
Click to expand...

I do plan on testing it again, I never trust one test. But, believe me, it was pretty definitive. The shallow end took 20 lbs of pressure then blew my pressure test cap off. The deep end never got past .5 lbs no matter how much air I pumped in. I changed caps at the pool end, had someone watching for leaking air, etc. No way to get the line to pressurize. When I get the chance, I am going to retest the pressure AND then I am going to cap the line and fill the return with water and see if it leaks.

Right now, I have that line sealed off. I am filling the pool back to the normal fill (has been down about 6" for the last 4 weeks or so). It is still warm enough for the solar to run and everything else, so I should get a good feel if that is where the leak is over the next few days.
 
Update.

Even though I was pretty confident that the leak was in the deep end return, I got a little worried because the pool continued to go down. I decided to pressure test again. Lo & behold, the cap I put on that return line (inside a union) had turned sideways, letting water enter the line - though not the pool since the return was capped at the pool. I pressure tested and the line would still not hold pressure. This time, I had my wife listen at the return end, sure enough, we could hear air (and water when I filled the line) hissing out, just behind the pool wall.

Then I filled the line with water and it immediately leaked down. Whew! At least I had found the leak!

So, it appears the leak is where I thought it was - where the flex pvc line connects to the return wall fitting. It appears that the flex line goes OVER the fitting. Not sure if the leak is due to a poor glue job or a crack in the line (doubtful) or fitting (possible). I left the pump completely off and the return sealed at the pool and the water loss has stopped!! Yee haw.

I have called my PB several times, but true to form have not gotten a return call yet. I REALLY do not want to tear up a lot of concrete, so I am considering trying to seal the leak by caulking or gluing at the seam where the flex line comes over the fitting. I can just reach that point with my finger and could easily get there with a flat stick of some sort. I am thinking that there really isn't much pressure there and if I can get a good seal, it might work (at least for a while).

I remember reading on the old PoolForum about a PVC epoxy that sticks to PVC and is pressure rated, does anyone know what I'm talking about? I thought I had the website that sells it in my bookmarks, but can't find it.

Any other suggestions for trying to fix this type of leak? I am considering just closing the pool at this point and delaying a fix until spring, but I know I would be thinking of the d*mn thing all winter, so I'll probably push ahead. Any help, suggestions would be appreciated.
 

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Nice detective work. For the life of me, I still have no explanation for the bubbles in the return line.

I think I have the leak location in my minds eye (behind the pool wall, at the point where the flex joins the back of the return fixture) and, if that's the right location, any two-part medium to heavy bodied epoxy should work very well and relatively easy to apply with a tongue depressor type stick.
 
Now the water level is just at the top of the returns. And, I notice that the return in the deep end is now blowing lots of bubbles.
Click to expand...
Not sure why, but your problem (at least the bubbles issue) is still really puzzling to me. Taking the quote above from your original post, wouldn't that mean that the water level in the pool was below the skimmers as well? If so, the skimmers would be the obvious source of the bubbles.
 
The skimmers were valved off long before the water got that low. Again, from my original post, there was no air in the pump basket, no air in the filter (bleeder valve checked) and no air coming from the other return. I have sucked air through my skimmers before and it ALWAYS resulted in air in both the pump basket and filter.

I also eliminated the possibility of a "suction venturi" happening right at the pool side of the return (when the water gets just a little bit below the top of the return and air is sucked into the water stream) by attaching a small section of PVC with a 45 in it to direct the water down into the pool (I use these in the spring when starting up to direct warm water down into the pool). These little rigs are glued, so no air can get pulled in (unless my glue job is as bad as my PB) and I made sure the threads were sealed with teflon tape.

The bubbles only happen when the water is within about 1/4" of the top of the return. If the water is deeper, no bubbles (even when the water is below the skimmers). I wish I could explain it too!
 
OK, I went into the 49 degree water to try and fix this leak. I used Plast-Aid, which is good stuff, but it takes a while to set up to the point that it will correctly stick on the TOP inside of a pipe. Anyway, it didn't work, I wasn't able to seal the leak. One of 2 things - I didn't get a good seal around the joint OR the leak is a little further in. To explain, turns out that the flex PVC doesn't directly connect to the wall fitting. There is a very short pipe run, then a 90 elbow, then the flex pipe goes into that.

I am thinking that the leak is at the top of either the wall fitting or the 90 fitting because when I removed the stop fitting on the wall, I got a small amount of water that was still in the pipe drain into the pool. If it was at the bottom of the 90, that would not have happened (I believe). The water was just too cold to stay in long enough to do this right, so I sealed the sucker up and closed the pool. I hate having to deal with this in the spring because that means I will have to drain the pool down again - we count on the winter/spring snow & rain to fill the pool back up for opening. But, I might be able to do a dye test to determine exactly where the leak is then.

Anyway, thanks to everyone for their help. Hopefully I can report success (which mean no concrete cutting!!!) in the spring.
 
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