How much chlorine for Breakpoint Chlorination?

[Swimmerick]

Hi! I'm new to the forum, and I'm excited to participate!

I need help determining how much chlorine to add (and what form to use) to exceed Breakpoint. I have a roughly 25k gal vinyl lined pool with a Pentair Intellichlor SWG and a sand filter.

Stats from my Taylor K-2006C test kit:
NaCl = 2600 ppm
FC = 0.6 ppm
CC = 0.8 ppm (first time in 4 years since I bought the house where CC > FC)
Total Alkalinity = 80 ppm
pH = 8.0+
Calcium Hardness = 100 ppm
Saturation Index ~+0.03

I've been reading online and figured I need to do a Breakpoint Chlorination to lower the CC, and I could use some help figuring out how much chlorine to add to make sure I exceed Breakpoint.

 

[mknauss]

Welcome to the forum!
Breakpoint is a pool store term. It does not really mean anything.
Your pool needs chlorine. What is the CYA? What does the water look like?
I suggest you read ABC's of Pool Water Chemistry.

 

[YippeeSkippy]

Well, you obviously need MORE CHLORINE!! Chlorine and CYA must be kept in balance according to this chart- FC/CYA Levels
Pick the SWG side of the chart.

If you're just how starting the SWG up, make sure your FC level is brought up with liquid chlorine first, then let the SWG maintain that level. It works too slowly to bring your FC up to needed levels before algae crashes the party.

Maddie

 

[Saturn94]

Your salt level seems low. Is your SWCG producing chlorine?

 

[Jimrahbe]

Rick,

I agree with Saturn94... Your Salt level is way too low...

You need to get some Liquid Chlorine into your pool ASAP...

As a minimum I'd add a gallon of 10% Liquid Chlorine.. Maybe much more depending on the CYA level, which you failed to list.

Thanks,

Jim R.

 

[Swimmerick]

My test kit says Salt should be 2500 to 3500 ppm, and I usually keep it above 3000. I know it's low and I've added more salt.

I still need to add chlorine, but I don't want to add too little. According to what I've read, I need to add at least or more than the breakpoint or I could end up needing to drain the pool.

Https://www.in.gov/isdh/files/How_To_Shock_The_Pool.pdf

What I haven't been able to figure out is how to calculate the needed chlorine. According to my numbers, I need to make up at least 7.4 ppm but I don't know how to determine the quantity of chlorine that is required to do that.

Can anyone help with that calculation?

 

[Swimmerick]

P.s. The water is currently crystal clear.

 

[Swimmerick]

Also, I've never gotten a meaningful result from a CYA test. The instructions are to add reagent to the water sample, mix, then pour the cloudy mixture into the test tube until the black dot at the bottom disappears. EVERY time I've done this test, the sample is clear, never cloudy.

 

[HermanTX]

Also, I've never gotten a meaningful result from a CYA test. The instructions are to add reagent to the water sample, mix, then pour the cloudy mixture into the test tube until the black dot at the bottom disappears. EVERY time I've done this test, the sample is clear, never cloudy.

That means you have zero CYA which is why you are not seeing any FC because the UV is consuming it.
download the app PoolMath
Fill out your pool details and it will tell you how much chlorine to add to be safe.

 

[HermanTX]

PoolMath

 

[Saturn94]

Welcome to the forum!
Breakpoint is a pool store term. It does not really mean anything.
Your pool needs chlorine. What is the CYA? What does the water look like?
I suggest you read ABC's of Pool Water Chemistry.

This!

To the OP, please read the link mknauss provided. There is a section about CC and how to address excess CC levels. Also, the Pool Math link Herman TX provided will help with dosing calculations.

 

[Kellyp]

Also, I've never gotten a meaningful result from a CYA test. The instructions are to add reagent to the water sample, mix, then pour the cloudy mixture into the test tube until the black dot at the bottom disappears. EVERY time I've done this test, the sample is clear, never cloudy.

Have you ever added cyanuric acid? Aka cya, aka stabilizer? If you haven't, then you won't have any. It is sunscreen for your chlorine and the cya/chlorine relationship is the foundation of TFP.

Def read the ABC's linked to earlier, ask about anything you're unsure of.