CYA from Trichlor

VeronicaKG

Well-known member
May 1, 2019
55
Mentone, CA
I recently had a Reverse Osmosis treatment due to excessive CH. After it was finished the water was balanced by the technician performing the R/O . Everything balanced out just fine except the CYA measured 0. I contacted the R/O tech and he said don't add any stabilizer because he already added 25 ppm. (Just how he added it I don't know} The CYA finally did show up on the test about a week later. A few days after the R/O was done I had gone to the pool store to buy some MA and decided to get a free water test. The person working there stubbornly tried to sell me some stabilizer telling me I had 0 CYA. I then told him that it was probably undissolved in the filter and I was going to wait at least a few days to be sure there was truly only 0 CYA. Good thing I did!

The thing is I've been using Trichlor pucks to try and bring the CYA just up to 30. (Out here where I come from it's called getting all pucked up!) According to the pool calculator the amount of Trichlor I've just used should of brought my CYA levels to 30.

Is there a delayed time that CYA from Trichlor will show up in a test?

I use both the the Taylor and the Blue Devil CYA test kits. Both tests consistently show CYA 25.

FC 3.5
CC 0
TA 110
CH 190
CYA 25
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,396
Laughlin, NV
A CYA of 25 is not measurable. The tube for testing is logarithmic. So interpolating between 20 and 30 is not viable. Call it 30ppm.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,396
Laughlin, NV
Isn't 20 to 100ppm measurable by using the Blue Devil and the Taylor 9193 comparators? Or is it just not measurable under 30 period?
Absolutely - but - not 25 or 32 or 44. The test does not have that resolution. Round up to the next whole amount.
When you do the CYA test, try this next time.

Once you have your solution ready, back to the sun, etc. Fill the vial to a line, say 80, lower the vial to your waist level and glance for the dot, you see it, add solution to the 70 line, glance, see it, repeat until you no longer see it with a glance. Then use the CYA value one step above the line you read. So if you stopped at 50, use 60 ppm CYA.

The vial is in logarithmic scale. So it is not viable to interpolate between the lines. Just use the whole numbers, such as 50, 40, 30, ....
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,396
Laughlin, NV
Shouldn't . But you need 10-15 ppm worth for it to show up. The CYA test just does not have the resolution you think it does.
 

VeronicaKG

Well-known member
May 1, 2019
55
Mentone, CA
I guess I'll just have to see how quickly my CL goes. The first day after the R/O I was dumping gallons of LC into the pool and it just vanished so fast because probably the CYA the R/O tech put in went straight to the filter. Before the R/O my daily CL loss was only about 1ppm per day. Now its up to 2ppm. I'm thinking I need just a little bit more CYA. Before when my daily CL loss was 1ppm per day my CYA tested at 30ppm.
 

VeronicaKG

Well-known member
May 1, 2019
55
Mentone, CA
Been testing each time I add more. Still not quite to the 30ppm mark on both tests I use. The R/O tech may of added less then 25ppm is my only thought. The CYA was added on the 8th of June so surely by now wherever it went it would be dissolved by now.
 

JamesW

TFP Expert
Mar 2, 2011
16,339
Most pucks are 7 oz. so 49 ounces will raise the CYA by 10 ppm.

Even if we use 8 oz per puck, that’s 56 oz, which will add 12 ppm CYA.

 

VeronicaKG

Well-known member
May 1, 2019
55
Mentone, CA
Its like not enough too much stabilizer, too much not good. My only solution is to keep testing the CYA levels and hope they don't rise too high out of nowhere.
 
Last edited:

JamesW

TFP Expert
Mar 2, 2011
16,339
According to the pool calculator the amount of Trichlor I've just used should of brought my CYA levels to 30.
I think that part of the problem is that you're miscalculating the effect of the trichlor. You're expecting to see a 30 ppm rise when it should only be 10 ppm.
 

VeronicaKG

Well-known member
May 1, 2019
55
Mentone, CA
But it tested between 20 and 30 before I added the Trichlor. I was merely trying to bump up the the level closer to 30 but its taking more Trichlor than what the calculator is showing.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,396
Laughlin, NV
There is some natural loss of CYA, primarily during the summer and warmer pool water temperature months. You may be seeing some of that.

Add a couple more pucks. Having a CYA of 40 or 50 ppm in your climate is not a bad thing. Just adjust your target range FC.
 

VeronicaKG

Well-known member
May 1, 2019
55
Mentone, CA
Ok I will watch cautiously. Last season I luckily caught it in time as I first started reading this forum and learned about the problem of getting too much CYA through the use of Trichlor. Thanks for all the replies!