Wallyworld chlorine VS pool store, experiment time

[MikeInNH]

I recently ran out of the 5 gallon pail of pool store 12.5% Chlorine so grabbed 2 bottles of Wallyworld brand 6%. Last night I put in what I think was similar amounts of 6% compared to what I normally do with the 12.5%. Interesting thing is, late this morning I checked the Cl level and it was twice as high as I get with the bulk amount. Now I feel the need to do a controlled experiment to see if it was a fluke or if the pool store stuff is not as potent as I thought. Time will tell.

 

[reebok]

it's unlikely that it's still 12.5% but I will be interested to see your results. would be good if you could exapnd on "what I think was similar amounts".

 

[Bama Rambler]

That's a good idea. Let us know what you find out. I'd like to know what you consider a similar amount? Twice as much 6 as 12???

Along those lines I'm using almost the same amount of 10.5% per day as I was 6%. Kinda makes you go, HMMM don't it?

 

[CurtisT]

Lowe's here in Houston carries the 10.5% and it's stored in the garden center in the heat. Also, I doubt they turn it over very quick which has me a little concerned about what strength I'm getting. Warehouse Pool Supply keeps theirs outdoors, but they tell me they go through a couple of pallets a week, so I assume it's relatively fresh. Still, I feel more confident with the Wal-Mart 182 oz jugs that I know are re-stocked pretty much daily and are kept in A/C all the time (well, all the time once they are on the shelf... I don't know where they keep them before that).

 

[MikeInNH]

You ask what I call similar amounts, it would be the amount I need to put in to do the same as what the 12.5% would do. At least in my mind In this case it was about 1/3 of the 1.4 "great value" bleach. I was guessing this was a bit more than double what I do with the 12.5%, my Cl levels were virtually non-existant....oops. So. it's now been about 36 hours and I just did a reading, the Cl level is in the 1-2 range. I don't remember the 12.5% ever holding that well. This time I added the exact same volume of 6% that I do of the 12.5% every day or other day depending on the sun. It's supposed to be hot and sunny today so I'm making the Cl on the high side. First hot day this year.

I'm wondering if a sealed Walmart bottle of bleach is better than doing the big 5 gallon buckets. Maybe the Cl in the latter gets less potent starting the day you open it. Now I need to get to the pool store for the 12.5%.

 

[MikeInNH]

Well, I finally got around to some testing today. I used a dropper to put similar amounts of chlorine in a full bucket of pool water. I used the Walmart 6% (the bottle was opened a few days ago) and the 12.5% bulk bucket. The 12.5 was the last quart or so in the bucket so it's maybe been a month since I opened it. I tried to be as exact as I could. With the 6% I got 12PPM's and with the 12% I got 19PPM's. This is using the same dropper amount of chlorine for each so the 12.5 should be double. I assume it degraded over the last month so the drop isn't too bad. Makes me think that I will only use the big stuff for the spring shock and then I'll run with the easily pourable 6% bottles the rest of the year. I'd like to see what a new bottle of 12.5% would show but seeing my pool is now 72F, I don't think I'll be buying anymore this year, at least not bulk. In testing I used the powder/drop test and checked the PPM's before and after adding the cl.

 

[teapot]

What sort of containers is it in, clear or black?

 

[PaulR]

With the 6% I got 12PPM's and with the 12% I got 19PPM's.

So if the 6% is really 6%, then the nominal 12.5% was really about 9.5%. (Here's a related tidbit: 1/2 tsp of 6% bleach in 4 gallons is pretty darn close to 10ppm. 1/2 tsp of 12.5% should read 20ppm.)

I looked at the numbers here and it's clear the decay is not your usual exponential decay even though it's described in terms of half-life. My best guess is that a 12.5-to-9.5 decay would take about 2 months at a constant 80F; less if warmer, more if cooler. If you've had it a month, and it's been warmer than that, it seems not unreasonable.
--paulr

 

[MikeInNH]

Teapot, the large bucket of 12.5% is a solid blue. I cannot see any light getting through there and it's never in the sun.

PaulR, we had a few weeks in August that it stayed in the 90's or high 80's plus this was the bottom of the bucket. I'm a bit surprised it fared this well. The bottom line is that 9.5% ends up costing more than the Walmart bottles so not worth the pain of the big jug except for shocking. Maybe I'll try testing again in the spring. :-D

 

[DCAG]

I never have much luck getting bleach at WalMart, the shelf's always empty. On the bright side for those of you in this part of the country, I have found Market Basket's regular 5.25% gallons are normally $1.50, and the Ultra is $2.00/gal
IMHO, the extra .75% is not worth the extra 50 cents.

Dan

(Market Basket is comparable to Krogers/Price Chopper)

 

[MikeInNH]

Aha, I'm sitting at my desk working in the town you live I live on the other side of the river.

 

[PaulR]

The bottom line is that 9.5% ends up costing more than the Walmart bottles so not worth the pain of the big jug except for shocking.

I hear ya. When my local pool store has 12.5% with a 2-for-1 deal, it beats anything else all hollow; otherwise it's the Target Clorox.
--paulr