Am I Losing My Mind? Intermittent Leak?

[Crashaxe]

I have a Poolmeiser (PM) auto leveler and the PB plumbed the equalizer line to the bottom of the skimmer about two inches from the skimmer pipe that runs to the pump (in attached photo from construction the lines to the PM from left to right are water supply, overflow drain, equalizer.


In normal operation everything is adjusted so the water level in the pool sits at 4" above the bottom of the skimmer opening.


When the pump is running the water level in the PM canister lowers about 1" (I assume because of proximity of the equalizer line to the skimmer suction) hard to see in this photo but it is right at 1" below the top of the overflow. The fill shutoff float is adjusted to turn off at this level.


When the pump shuts off, the level in the PM rises back to just below the overflow



If the pump is running during significant rainfall (like it was today 1.10" of rain in 30-40 minutes) the water level can rise about 1" in the pool before it will start to overflow and drain (which it did). In this case when the pump shutoff at 5pm the water level would have risen another inch in the PM and would start overflowing (which it did). Overflow should have stopped when the water level fell below the top of the overflow.

But, when I looked at the pool about 90 minutes after the pump shutoff I thought the water level looked low so I opened the PM cover and looked and sure enough the water was about 2" below the top of the overflow I didn't think to take a picture before I began checking everything and reseting it to normal but when I measured the water at the opening of the skimmer it was only about 2.5" above the bottom of the skimmer opening. Which was low enough that when I started the pump so the autofill would top off to the right level the skimmer was starting to suck air and I had the close the skimmer suction valve while it primed at 100% speed. After 3 minutes the VS Pump adjusted to the normal 75% speed and I was able to re-open the skimmer suction. The PM topped the pool back off as expected and the level has been holding for 2 hours now with the pump off.

This also happened one other time two or three weeks ago but it was the day after I had adjusted the PM fill and overflow levels and I thought I had failed to push the overflow pipe all the way into the bottom of the PM. I pushed down on the overflow pipe again tonight when this happened and it may have pushed down slightly but it wasn't all the way out for sure.

Am I crazy? What could explain this intermittent water loss after heavy rain and high pool level? A leak? Could the overflow pipe be working loose somehow and cause this? other ideas? Has anyone else experienced this before?

Photos of my equipment pad and valve settings are below, this is my normal setup with the spillover spa, and haven't had any issues as I said for two or three weeks since the last time this happened.

 

[Texas Splash]

I don't see a leak scenario at this point, otherwise you would have consistent water loss and low water levels. Since it's intermittent, I wonder if the float itself has been getting stuck on occasion? By any chance do you see any correlation between the PM and pool level compared to the spa water level?

 

[Crashaxe]

@Texas Splash that's what I was thinking but I can't seem to figure it out in my mind. The spa level stays very consistent sitting right at the bottom of the spillway when off and never dropping lower unless we were to climb in and displace water from it.

The original float was not shutting off all the way but that was replace a week or so before the first time this happened. If the float were stuck closed then evaporation could let the level get too low I suppose. But in this scenario water went from 1" above overflow to 1" below overflow in the span of about 1 -2 hours. Heavy rain raised the pool level around 1" higher than normal (right to the top of the overflow with pump running).

I think there should only be two ways to drain water from the pool: 1. the PM overflow; and 2. the waste valve just after the pump but before the filter. Other than that it is a closed system... I am stumped.

 

[Hootz]

Something doesn’t seem right with the poolmiser water source. You should not have been able to see the level low in the poolmiser basin…it should have made up the difference from the external water source.
quote : “Which was low enough that when I started the pump so the autofill would top off to the right level”
You should not have to run the pump in order for the poolmiser to top off the pool level.
This doesn’t explain why the level was so low after draining the overflow but the poolmiser should have made up the difference and you would not see the pool level low.

 

[Jimrahbe]

Crash,

Logic says that if you want to troubleshoot a pool leak, your auto fill should be shut off...

Thanks,

Jim R.

 

[Crashaxe]

Something doesn’t seem right with the poolmiser water source. You should not have been able to see the level low in the poolmiser basin…it should have made up the difference from the external water source.
quote : “Which was low enough that when I started the pump so the autofill would top off to the right level”
You should not have to run the pump in order for the poolmiser to top off the pool level.
This doesn’t explain why the level was so low after draining the overflow but the poolmiser should have made up the difference and you would not see the pool level low.

@Hootz because of my plumbing layout the suction from that provides the right amount of skimmer action also puts a small vacuum on the equalizer line resulting in a level inside the PM canister that is about one inch lower than the actual level of the pool. The PM float has been adjusted to shutoff at that level. If the PM is adjusted to shutoff at the "actual" pool level it will overfill during operation and drain an inch of water everyday. A diagram showing the layout of the plumbing is below:
The equalizer line should have been directly to the pool not through the skimmer that would take care of this problem but this is my first pool build and I didn't know what I didn't know or I would have had the PB correct before they did the shotcreete and poured the decking.

I agree it doesn't explain going from high level to too low without something else going on though.

 

[Crashaxe]

Crash,

Logic says that if you want to troubleshoot a pool leak, your auto fill should be shut off...

Thanks,

Jim R.

@Jimrahbe I agree that would make sense except it seems to happen only intermittently and if the pool is off the level can drop a full inch before the autofill will turn on.

 

[Jimrahbe]

Crash,

Pool leaks are not normally intermittent.. They tend to leak or not leak. They may only leak when the pump is on or off..

I guess my point was that when you are troubleshooting anything, you try to eliminate any outside variables.

If this was my pool, I'd shut off the auto fill early in the morning and measure the water level with a ruler, just like you did in your pics.. (I use a paint stir stick with markings as it shows the water level better when you take the stick out).. I'd either run the pump all day, or not at all, and then measure it again after about 10 or 12 hours and see if you are actually losing water or not.

I don't fully understand how your auto fill plumbing works.. But don't see how that would cause a leak. It may not work the way you want, but is it causing a leak?

I guess another option (as a test) would be to temporarily plug the overflow and see what happens.

Thanks,

Jim R.

 

[hildebrau]

@Crashaxe , I think I experienced the same issue yesterday after a heavy rain. My belief is that the Poolmeiser lid was not allowing air into the bucket and a siphon started. I say this because I could not lift the lid with my fingers like normal. Once I pryed it up with a small screw driver, I saw the level of water decrease from slightly below the overflow pipe to down a few inches. My theory is that the water level was higher than the overflow pipe when I cracked the seal of the lid and by the time I lifted the lid it had already decreased the water level slightly and continued decreasing as I watched it level out with the pool... Which, sadly, was several inches below the overflow pipe height.

My planned fix is to drill a small hole or two into the lid to prevent a future vacuum/siphon scenario.

 

[DavidLast]

I am looking at the plant and wondering if there is a check valve in this circuit? I am wondering if the pool was to fill enough, could the head pressure be enough to start a reverse siphon?

 

[mas985]

I would never plumb an autofill into an equalizer line because if the equalizer valve in the skimmer leaks even a tiny bit, it will do exactly what you are seeing. The pressure at the tee is lower than the water pressure from the pool so the water level in the autofill will drop and open the fill valve even though it shouldn't.