Losing salt level

[Elgrecus]

I've noticed a slow but steady loss of salt in our pool. In early August our level was 5000 ppm (recommended by ECO-matic) and now (late November) is down to 3000 ppm. We've owned the house for one year, so we're just familiarizing ourselves with how the seasons affect the pool. I am using the Taylor K-1766 salt kit, so I believe the readings are accurate.

My understanding is that nothing should affect the salt level except for dilution. The sprinkler heads in our sprinkler system do have some overspray on the pool cover, and I believe some water may be getting in by running across the coping. But we only water two or three times a week for about 15 minutes. Based on the salt levels, that would mean we've lost, or poured in, 40% of the water. That would be about 3800 gallons. If it's the sprinklers, that would mean that about 80 gallons of fresh water are getting in the pool during each watering in that period. That seems like too large a number. So, is there a leak somewhere in the system? I don't think I've ever heard the leveler adding water and I believe it's a sound I would have noticed. How does one go about determining what the cause is? Am I overlooking some other possibility? Thanks in advance for your help.

 

[duraleigh]

Of course, this is speculation but I'll bet your auto-fill device is the issue.

You can google the average evaporative loss for your geographic area and see just how much your auto-fill has replaced.

 

[Elgrecus]

I was under the impression that when the water evaporates the salt does not. If the water is evaporating, I would expect the salt to be left behind. If the leveler is refilling the pool, wouldn't the salt level stay the same? Or is there some kind of overflow drain in the pool I am not aware of? Something like the overflow in a typical sink?

 

[jblizzle]

It could be that your pool has a leak that the auto fill is masking or that it is running and causing the pool to over flow.

 

[duraleigh]

Good morning!

Of course, you are correct about evaporation not being the culprit. My post was in error and am sorry I answered so quickly without thinking..

Masking a leak, as jblizzle suggests, might still be the fault of the autofill and that could contribute to your issue. I would suggest turning off the aut-fill and observing your pool level for a couple of days or so. That should uncover any significant leak.

Other than that, I am hard pressed to come up with a logical answer.

 

[Bama Rambler]

How much splash-out do you have?
How often do you backwash your DE filter?

 

[cbink]

I was under the impression that when the water evaporates the salt does not. If the water is evaporating, I would expect the salt to be left behind. If the leveler is refilling the pool, wouldn't the salt level stay the same? Or is there some kind of overflow drain in the pool I am not aware of? Something like the overflow in a typical sink?

There is often an overflow, though not all pool have one - Mine does, and for example and when it rains like it has the past few days here in Houston quite a lot of water goes out through the overflow and my salt level does drop.
It looks like a small grate and will be just above the waterline on the tile somewhere. Here's what mine looks like (this is from before the pool was finished but gives you an idea of what it may look like:

Mine is tied into my drainage and dumps water out to the street out front.

 

[Elgrecus]

Thanks for the responses. This summer we did splash a lot. Maybe not thousands of gallons worth, but a lot. The filter was overhauled a year ago. Since then I have not backwashed (still need to get that special hose for it). And I do not believe that there is an overflow in the pool, at least there is nothing resembling what cbink shows in the picture above.

By the way, how would I go about turning off the autofill? And as another note, we do live in Los Angeles so I expect a far amount of evaporation during the summer, but again, not thousands of gallons worth... although I could be wrong.

 

[ping]

There should be some sort of valve to shut off the autofill and it is most likely located where they tied the autofill line to the main water supply line.

Do you have a CYA test? You should be losing some on this test also if there is a leak.

Here in Long Beach, I lose about 2 to 3 inches of water a week due to evaporation during the summer, but that has nothing to due with losing salt.