How to calculate strength of aging chlorine

[atxjmy512]

I have some bottles of liquid chlorine that are clearly weekend in terms of current strength versus advertised strength. I’m not getting the expected rise in CL PPM when adding the Pool Math prescribed amount. How do I calculate the current strength of the chlorine in bottle so I can adjust the amount I add to get to the desired chlorine target?

If you look at my logs you can see my current bottle looks to be about half the expected strength.

 

[proavia]

If in your testing, the added amount gives about 1/2 the expected FC, add twice as much.
Your pool chemistry is ever changing. As such, it's not an exact science. If what you add isn't quite enough, add a little bit more chlorine. If you overshoot a few ppm, that's fine too.

 

[atxjmy512]

If in your testing, the added amount gives about 1/2 the expected FC, add twice as much.
Your pool chemistry is ever changing. As such, it's not an exact science. If what you add isn't quite enough, add a little bit more chlorine. If you overshoot a few ppm, that's fine too.

This one was easy because of the obvious half strength. Generally speaking though I should calculate strength in terms of performance to expected FC rise? For instance if I’m expecting a rise of 3 ppm and I only get 1, call that 1/3 strength and multiply expected chlorine dose by 3?

 

[Mdragger88]

This one was easy because of the obvious half strength. Generally speaking though I should calculate strength in terms of performance to expected FC rise? For instance if I’m expecting a rise of 3 ppm and I only get 1, call that 1/3 strength and multiply expected chlorine dose by 3?

Yes

 

[C3Cl3N3O3]

1/2 strength is pretty horrible, I hope I don't encounter that problem.

 

[Mdragger88]

1/2 strength is pretty horrible, I hope I don't encounter that problem.

I run into this when using leftover bleach from the pool season - during the winter i keep some for my spa but I don’t use large amounts. no biggie just use more. Some chlorine is better than no chlorine. Waste not want not

 

[ajw22]

Breakdown of Bleach Over Time by Storage Temp - Further Reading

www.troublefreepool.com

 

[PoolStored]

1. Taylor Bleach Test Kit
2. Take 0.1ml of your "bleach" and dilute to 1 liter. Test this sample as you would your pool/spa sample (10 ml using the FAS-DPD) method. The result, in this case, is pph (%) rather than ppm. For example, a 6% bleach concentration will yield 6 as the test result.
3. Pour it into my pool and see how it does.

 

[C3Cl3N3O3]

Breakdown of Bleach Over Time by Storage Temp - Further Reading

www.troublefreepool.com

That's helpful. I store mine at 75 degrees for 2 weeks at the most, so there isn't much loss there. Unless, of course, it was "pre-aged" at the store.

 

[atxjmy512]

That's helpful. I store mine at 75 degrees for 2 weeks at the most, so there isn't much loss there. Unless, of course, it was "pre-aged" at the store.

Yeah I’m not too thrilled with 1/2 strength. It’s a recently purchased bottle of 12.5% from Leslie’s (I had unused rewards points). I can’t see a date printed on the bottle so no clue how old it actually is. As far as storage I’m in Central Texas and there’s just no place I can store pool chemicals where it doesn’t get exposed to warmer temps. The best I can do is a shaded spot next to my garage in a Rubbermaid bin and cycle through it quickly.

 

[an1vrsy]

How many jugs do you keep on hand? How big is your laundry room? I have a SWG so I only keep, like 2 jugs around at a time. Those 2 jugs are in my laundry room.

 

[Mdragger88]

I keep mine in the shade under my deck year round. In the summer I cycle through it quickly enough that it doesn’t deteriorate too bad. It’s surprisingly cool under there. I am fortunate enough to get fresh stuff that’s approximately 11% the day they fill it. I just use 10% in poolmath all the time & generally always hit or slightly exceed my target.