Chlorine usage high. Again

A_kraker99

Well-known member
Jul 18, 2015
103
Zeeland MI
OP, can you confirm that you are working with a true 12.5% CL? Even CL a month old stored indoors can loose potency.
I don't know how to confirm that. I have done a FC test before and after adding a measured dosage and verified the FC increase was on par with what Pool Math says it should be. The chlorine does sit in a translucent Pentair dosing tank throughout the week (4 gallon capacity) and it is exposed to sun. Not sure how much that would affect the percentage.
 

beautifulpool

Silver Supporter
Jun 2, 2019
132
North TX
4 ppm per day is on the high side of normal. Many people on this forum report such losses. I have as much confidence as anyone can possibly have based the wisdom of this forum and my test results that my pool is quite healthy, yet I lose about 4 ppm of FC. My pool is fully exposed to the sun all day and naturally heats to the low 90s at times.

Higher CYA does not increase chlorine demand. It does adjust the target number upward, but that is a one-time addition. It actually reduces chlorine demand. For example, if you are at 30 CYA with a target of 3-6 FC, and lose three ppm per day, in a week you will have added 21 ppm. If you jump to 50 CYA and a target of 6-8, it's a one-time addition of 3 ppm, but if the daily UV loss drops to 2.5, you're 0.5 ppm ahead after only seven days. Make sense?

In my very limited experience, there are diminishing returns on chlorine protection and CYA. The difference of jumping from 30 to 40 in my pool was pretty noticeable, probably close to 1 ppm per day. The effects of jumping from 40 to 50 were far less obvious. As usual, it is a trial and error process.
👌
 

Chasarms

Silver Supporter
May 8, 2020
347
Dardenne Prairie, MO
I don't know how to confirm that. I have done a FC test before and after adding a measured dosage and verified the FC increase was on par with what Pool Math says it should be. The chlorine does sit in a translucent Pentair dosing tank throughout the week (4 gallon capacity) and it is exposed to sun. Not sure how much that would affect the percentage.
If the LC was fresh when poured into the tank, I seriously doubt you are seeing measurable degradation in seven days. I add three weeks of LC to my tank at a time and have not seen recordable declines in FC levels as the product ages, and I use 12.5% LC.

If you are testing FC before and after dosing and the numbers equate to pool math expectations, then it is not the LC product.

At some point after experimenting with your CYA target , you may just have to concede that it is your version of normal.
 

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
1,003
Oil City PA
I don't know how to confirm that. I have done a FC test before and after adding a measured dosage and verified the FC increase was on par with what Pool Math says it should be. The chlorine does sit in a translucent Pentair dosing tank throughout the week (4 gallon capacity) and it is exposed to sun. Not sure how much that would affect the percentage.
So you’re chlorinating via a dosing pump?