Do I have a leak?

[Obecalp86]

Hi all,

I’ve had a tiny suspicion about a leak over the summer based on the auto valve being on a “lot”, meaning a soft intermittent “hiss” as it releases water (although we’ve had a record summer in Phoenix) and my salt level dropping as follows:

7/4: 3800
8/31: 3600
9/28: 3200

In the same period of time, my CH has gone from ~320 to 400 (my fill water is ~175ppm).

I did the bucket test - the tape was placed right at the water line outside the bucket, but probably 0.1 inch in the water on the inside, which I adjusted for in the pictures taken at 24 hours (see attachments). I also added a picture of the vigorous flow from the auto filler once I turned it back on.

Do I have a leak? Of note, our water consumption varies wildly month to month (we were mostly away all of July), but usage past few months seems in line with prior use).

Should I repeat with a see-through bucket to make this test easier?

Thanks all!

Edit:
- I cleaned filters last week and lost at least 10-20 gallon to bleeding air out of the filter housing, draining the filter etc
- Definitely no leak around the pool equipment
- pool patio is concrete and surrounded by pebbles, so I imagine a leak would be hard to spot, but at least there are no soft areas

 

[ajw22]

What is your water temperature?

What is the daytime air temperature?

What is the nighttime low temperature?

Is your pool covered?

Evaporation of Pool Water - Further Reading

www.troublefreepool.com

 

[Obecalp86]

What is your water temperature?

What is the daytime air temperature?

What is the nighttime low temperature?

Is your pool covered?

Evaporation of Pool Water - Further Reading

www.troublefreepool.com

Water temp is 86F.
Day time air temp was 112 yesterday and 80 at night.

Not covered.

 

[ajw22]

0.25” water loss in 24 hours can be evaporation.

 

[Obecalp86]

0.25” water loss in 24 hours can be evaporation.

But the water loss from the pool is about 0.8 inch and the difference between inside/outside the bucket is at least 0.15 inch. How big of a difference is “significant”?

 

[ajw22]

But the water loss from the pool is about 0.8 inch and the difference between inside/outside the bucket is at least 0.15 inch. How big of a difference is “significant”?

More then 0.15”.

 

[TinFoilHat]

Evaporation will leave CH and salt behind, a leak will take CH and salt with it. The auto fill will replace the CH but at a lower level of about 150. Your salt level would go down with a leak but your CH should go down too. Your CYA would also be depleted quicker than normal.

 

[Obecalp86]

Evaporation will leave CH and salt behind, a leak will take CH and salt with it. The auto fill will replace the CH but at a lower level of about 150. Your salt level would go down with a leak but your CH should go down too. Your CYA would also be depleted quicker than normal.

I understand these simple principles well, but how do you explain the drop in salt level? I think I lose 10-15 CYA per month (at least when water temps are in the 80’s-90’s), but I supplement my SWCG with old pucks specifically to get my CYA up (target is 80, I’m currently at 60, and started with 30ppm 3/2024 after I replastered my pool), probably at least meeting the loss of CYA from water temps. Also, I think it’s hard to make sense of a stable CH when my supply water has a CH of 175ppm as this makes CH loss from a leak less apparent.

I’ll post see-through water bucket test pics later today.

 

[Obecalp86]

I tried the clear bucket method and get differences (lower waterline on the outside) from 0.2 inches to 0.3 inches (see pics - the ruler is in cm and I converted it to exact numbers in inches).

I didn’t realize how difficult this test is.

Is this conclusive or is there some other test I can do? I would rather not pay $600 to a leak detection company to be told I don’t have a leak.

 

[Obecalp86]

Just in case anyone might find this useful - I redid the bucket test with a better (easier to see) setup after my salt level dropped 800ppm in a single month.

The bucket test is clearly positive - see pic.

Leak company coming out this week to do pressure testing. Will add a comment once I have results.

Trust the bucket test.

 

[Obecalp86]

Turns out there was a leak in the skimmer throat grout joint. Easy fix.