The 10% Solution

[AnnaK]

Recently we had a discussion of grocery store bleach vs chlorinating liquid and the relative merits of each in view of concentration and degradation.

I buy chlorinating liquid from the pool store in 5 gallon carboys for $14.75 plus tax. It is said to be 12.5% and I don't doubt that's true at the moment of manufacture but I'm sure it has degraded to some extent by the time I use it. When I input the different variables in the Pool Calculator I've commonly used 10% as my chlorinating liquid concentration.

Today I decided to do the actual testing using a 5 ml pipette and a 50 ml graduated cylinder. I made a dilution of 1 ml : 100 ml, mixed it well, and made a second 1:100 dilution. Then I tested two samples, a 25 ml using the 0.2 multiplication factor and a 10 ml using the 0.5 factor.

My results were 9.4 ppm in the first and 11 ppm in the second sample. That's close enough to 10% for kitchen counter chemistry.

 

[duraleigh]

Nice work, Anna. I appreciate that experiment. I, too, purchase 12% and I know they get a very quick turnover but I still feel by the time I use it, I am down around 10%.

It's nice to have that somewhat confirmed.

 

[AnnaK]

I think going with the assumption of 10% is good enough for our purposes of maintaining a reasonable level of FC given the many variables we deal with in any given 24 hour period.

 

[AV8TOR]

I buy chlorinating liquid from the pool store in 5 gallon carboys for $14.75 plus tax. It is said to be 12.5%

What pool store are you getting that at?

 

[AnnaK]

A locally owned store in eastern PA.

 

[257WbyMag]

I buy chlorinating liquid from the pool store in 5 gallon carboys for $14.75 plus tax. It is said to be 12.5%

What pool store are you getting that at?

Probably not going to find anything like that in our neck of the woods AV8TOR. Trust me on this, I have checked and asked ad nauseum. DFW pool stores just don't want to play that way. Even my own, non-Leslies, local pool store who will get me anything that I need stopped short of offering that. He qualified this by saying that there isn't enough demand for it. I thought that was particularly amusing because the stores around here can't keep up hardly with the bottled bleach demand during the spring around here.

By the way, I like your avatar. :-D

 

[CaOCl2]

Also what I noticed is that the major chains here, when the pool season starts, they pull out their "Pool Opening Kits" (from last year most probably) and ... their bleach, also from whatever stock was leftover from the year before.

I remember testing a "Purox" jug, advertised as 12%, and it tested out, if I remember, at around 5%. So just make sure whatever you're getting is fresh (not old stock).

It may not be an issue where you live because of the quick stock turnover, but up here, given the short swim season, it sure is!

 

[duraleigh]

In larger cities, you can sometimes find a business that supplies Pumps, parts, and commercial pressure washers for the commercial pressure washing industry, (In Raleigh, it's a national company called "Alanda")

This branch also stocks liquid chlorine. The manager told me they get in big, caged containers about every 2-3 weeks and refill them into the 5-gal carboys. He says it is guaranteed by his supplier to be 12% at time of delivery. That's probably a lot fresher than pool stores but maybe hard to find in your particular area.

I pay right around $13.00 for 5 gallons