Where did all my chemicals go?

lilredhen

Active member
Jul 29, 2009
28
Northern California
End of last summer I had:

TA 120
CH 240
CYA 70
Borates 50

This week I had:

TA 80
CH 70
CYA 0 (less than 20 anyway)
Borates 10

The Pool Calculator tells me I would have had to drain 70-80% to drop the levels like that. Could I really have lost that much or do I probably have a leak? I use a autofill system.

25,000 gal IG colored plaster pool, 6 years old w/ cartridge filter
 

loughps

Well-known member
Apr 26, 2009
221
Northeast Ohio
I'd suggest turning off the autofill and check for a leak. If it was only CYA, I'd say "That can happen, although it doesn't always", but since TA and CH dropped, I'd be searching for a leak.
 

lilredhen

Active member
Jul 29, 2009
28
Northern California
Thanks everyone and svenpup thanks for the link.

I checked for air in the pump basket - none and no bubbles in the pool. I checked around the equip pad for wet spots. Nothing.

Next should I just shut off the autofill and wait? I won't worry about evaporation with the cover closed. Should I have the pump turned off for this test?

25,000 gal IG colored plaster pool, 6 years old w/ cartridge filter
 

loughps

Well-known member
Apr 26, 2009
221
Northeast Ohio
I'd turn off the autofill and leave everything else "as-is". If your level drops less than an inch, you may want to put a bucket next to it to check for evaporation all the same (don't know if your cover is mesh, or how that impacts evaporation.)

Just getting the autofill turned off should let you see what's going on with the level. Just watch your water level so it doesn't get too low.
 

lilredhen

Active member
Jul 29, 2009
28
Northern California
I use the TF100 kit.

I'll mark my water level as soon as the kids are out of the pool, then see how much it drops in 24 hours. Will you guys be around tomorrow? LOL! :lol: Just kidding I know someone is always here when I need help! You guys are awesome!

Jill
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
Water replacement seems like the leading theory, but there is another way this could have happened, though it seems much less likely. TA and CH both go down when there is calcium scaling. CYA can vanish over the winter. And the borate test is difficult to read with any precision, so the change in borates might not be real, or might be smaller than indicated. That requires three separate things to have happened, while water replacement only requires a leak and an autofill, but it isn't impossible.
 

lilredhen

Active member
Jul 29, 2009
28
Northern California
So I thought my test was foiled by the unexpected rain we got today. But despite the rain I lost 3/8 inch in 24 hours.

Now to find whether a leak is in the pool or the plumbing, what do you suggest I do? The instructions on leak detection say to plug the skimmers and drains but I can't think of any way to do that. Has anyone done this before?

Jill
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
How many inches of rain do you get in the winter? does that get into the pool (cover solid or mesh?)
 

lilredhen

Active member
Jul 29, 2009
28
Northern California
After doing a search I found a test I could perform:

cya-dropped-from-50-to-20-t23869.html?hilit=pool leak

My result was 1/2 inch loss with pump off vs. 3/4 inch loss with pump on. This would indicate a leak on the suction side of the plumbing. Of course I could have more than 1 leak.

At this point is there a way to find the leak myself or is it time to call in the pool service? If I could find the leak I would probably have to have an expert fix it, but my local plumber would surely charge me less than the out-of-town pool service would. Any ideas?
 

Other Threads of Interest