Bleach - Check your date code

red-beard

Gold Supporter
May 27, 2019
487
Houston, TX
Chlorine loss is real. I switched to liquid bleach, 10% from Home Depot. My FC was low at the end of the day. So, I ran a test on the bleach.

First attempt:

1 drop = 20 ml. Mix 1 drop into 500 ml FC tested tap water. (Mine is 2 ppm Chloramine!)

0.05 ml / 500 ml = 100 ppm test solution

Why 100 ppm? If the bleach is 10%, this should make a 10 ppm test

Test failed. I am not sure if the drop was 1/20 ml. Came out about 1-2%. (Edit: I think I know why it failed. Need to add extra DPD powder for higher chlorine tests).

Re-test

1 ml / 500 ml = 2000 ppm test solution. Then diluted again 10 to 1. This would be a 200 PPM solution. With 10% bleach, I should have 20 ppm FC.

Testing this, and it requires a lot more DPD powder - 14 ppm. It should have been 20 ppm! My bleach is 1/3 gone! Date code 20-123, So, about May 2nd, 2020. So it is 97 days old and 1/3 gone. Stored in a 95 degree garage in Houston.

After testing the pool this morning, I added 50 oz. After the bleach test, I added another 50 oz. This should get me to my needed 6.0 ppm level in the pool. (Edit: It went to 6.8, so I adjusted my numbers above to reflect 7% bleach instead of 5%.)

I think I need to tighten up my test procedure, but I think in general it is valid. I would really like to get the 1 drop to 500 ml tap water to work, as that should read PPM = % bleach.
 

epro05

Bronze Supporter
Jun 5, 2014
307
Keller, Texas
A 0.3 ml syringe is very accurate, if you can acquire one. Fill it to 0.1ml and add to 1 liter of distilled water. I weigh out 1000 g of water (=1000 ml).
 

red-beard

Gold Supporter
May 27, 2019
487
Houston, TX
I have 10 ml syringes. I just ordered some 1 ml. That way I can adjust the formula and be a bit more accurate. Cal Hypo is way easier and doesn't degrade, or not as fast. Of course, there is the issue of the calcium buildup. But it doesn't happen anywhere near as fast as CYA.
 

borjis

LifeTime Supporter
Aug 19, 2014
3,281
Pacific NW
So, about May 2nd, 2020. So it is 97 days old and 1/3 gone. Stored in a 95 degree garage in Houston.
This is typical unfortunately. Many have noticed the hdx pallets stored outside in direct sun. It ends up less than the percentage you paid for.

I store my bleach inside the laundry room. Garage gets too hot and degrades it further. In this case, heat is the enemy.