Higher CYA = less frequent chlorine adds??

AndyTN

Bronze Supporter
Mar 27, 2019
149
Memphis
Something which is making me curious since I use liquid chlorine as my main source but still run my Rainbow feeder on the lowest setting for the triclor to supplement as a buffer. If low CYA below 20 is going to burn off FC quickly and high CYA above 70 will lock it up, I am understanding the principle of the CYA acting as a buffer to hold back the FC.

So assuming I am adding the same amount of bleach at 3-4 gallons 12.5% per week, if I have a CYA of 50, will this allow me to add the bleach less frequently than CYA at 30? Assuming my base FC target is kept in the range of the CYA chart. For example, CYA at 30 would require adding 1/2 gal daily but will CYA of 50 allow me to add 1.5 gallons every 3 days since the higher CYA will slow down FC loss?

My CYA is at 40 right now and I have no problems at all so this is hypothetical. Just trying to determine if I can save a little time during the work week with less frequent FC additions. I am almost out of trichlor for the season so no more CYA will be added for the rest of the year after a week or two more.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,396
Laughlin, NV
No. You should be replacing your FC lost each day. Not doing so allows the FC to drop below minimum.

Using trichlor continuously increases CYA. And thus, your FC level needs to increase in lock step. Much easier to add stabilizer to a certain level and manage FC for that level.
 

AndyTN

Bronze Supporter
Mar 27, 2019
149
Memphis
Using trichlor continuously increases CYA. And thus, your FC level needs to increase in lock step. Much easier to add stabilizer to a certain level and manage FC for that level.
After using TFP the past few years, I am very aware of the CYA effects of trichlor and water in Memphis is super cheap for a water exchange. I go through 1 trichlor puck per week and 3.5 gallons of 12% bleach per week so according to PoolMath, 88% of my FC comes from bleach. We get a lot of rain in the Spring and my CYA has risen from 30 to 40 in 2.5 months so far. Not questioning TFP methods but just tinkering to determine what works best for me.

Higher CYA means you need higher FC and the higher the FC the faster it burns off.
So I have been told by TFP Experts that any FC level below SLAM level is safe for swimming. So if I have a CYA of 40, when my FC goes down to 4 and I add a gallon of 12.5% bleach, pool math says FC will rise to 9. If the ideal range for CYA 40 is FC 5-7, will this extra 2 ppm act as my buffer or will it just burn away much faster? Same question for adding 2 gallons of 12.5 bleach to raise it to 13 for the buffer of 6 ppm.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,344
Franklin, NC
After using TFP the past few years, I am very aware of the CYA effects of trichlor and water in Memphis is super cheap for a water exchange. I go through 1 trichlor puck per week and 3.5 gallons of 12% bleach per week so according to PoolMath, 88% of my FC comes from bleach. We get a lot of rain in the Spring and my CYA has risen from 30 to 40 in 2.5 months so far. Not questioning TFP methods but just tinkering to determine what works best for me.


So I have been told by TFP Experts that any FC level below SLAM level is safe for swimming. So if I have a CYA of 40, when my FC goes down to 4 and I add a gallon of 12.5% bleach, pool math says FC will rise to 9. If the ideal range for CYA 40 is FC 5-7, will this extra 2 ppm act as my buffer or will it just burn away much faster? Same question for adding 2 gallons of 12.5 bleach to raise it to 13 for the buffer of 6 ppm.
Any FC above the Minimum will burn off faster.

Once I got a good idea of my pool's appetite for chlorine I just poured that much in each morning while I was drinikng my coffee.. Then I got lazy and installed a Stenner pump that just added what I needed each day.

 

aussieta

Gold Supporter
TFP Guide
there is no such thing as chlorine lock, that is pool shop garbage
what happens is the chlorine required to match your cya level is above their testing so they cant test anymore
chlorine burn off is a percentage of you total chlorine, so the higher you start the more burn off
a higher cya will slow this burn off
but if something goes wrong such as a compromised batch of chlorine your cya level will be too high to slam