Bleach Prices 2014

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how long will the 8.25% bleach last at 72-74 temperature? I'm afraid I'm going to have a couple dozens 64 oz bottles left for the next season. this summer is not as hot and may not last as long (northeast). + 8.25% is very good, 64 oz lasts longer than 24hr (I'd have 0.5ppm more same time the next day). I like it much better than 12.5% I used all these years. not sure why but it seems to last longer. I tested water using both at night a couple of hours after adding 64oz chlorine, results were as expected - matched pool calc, but 24 hours later I would have more FC with 8.25% HE. Maybe water temperature had something to do with it, the days I used 12.5% water (and the temperature outside) was more than 5 degrees warmer
 
See the table at the bottom of this link where you can see that the half-life of 8.25% bleach at 72-74 temperature would likely be around 600 days so it's not something to worry about. At the same temperature, 12.5% chlorinating liquid's half-life is around 250 days.

However, what you report seeing is completely different. You are measuring the expected FC a couple of hours after adding it (I assume this is after good circulation), but 24 hours later you have more FC with 8.25%. That makes no sense whatsoever. Once in the pool, the life of chlorine has nothing to do with its initial concentration. Yes, the warmer water temperature is very likely the reason the chlorine had more 24-hour loss. Roughly speaking, the chlorine reaction rates double every 13ºF so with a 5ºF increase in temperature the chlorine could get used up reacting with what is in the pool (or with a pool cover) 30% faster.
 
thanks, that makes sense. the 5+ degrees difference is the reason. Is there a difference between HE and regular bleach or it doesn't matter? how about the splash free ones?

also would it make sense to store bleach in the garage october-april, where temperature will be between 30-65 (vs 72-74)?
 
Target shoppers, don't forget to get the Cartwheel app for your smartphones. It's a target app that you use for coupons. It's extra 5% off the bleach right now and that's on top of the buy 3 get 1 free sale. Cartwheel coupons can always be used in addition to the current sales. You can use the app to scan items in the store and if there's a discount you add it to your "Cartwheel" and it gives a barcode for the cashier to scan for all your discounts when you check out.
 
nikon5400 said:
thanks, that makes sense. the 5+ degrees difference is the reason. Is there a difference between HE and regular bleach or it doesn't matter? how about the splash free ones?

also would it make sense to store bleach in the garage october-april, where temperature will be between 30-65 (vs 72-74)?
Click to expand...
You should not use Splash-less, outdoor, or scented bleaches since they contain additives you do not want in your pool. The thickeners in splash-less bleach will cause temporary foaming in the pool. The HE similarly contains thickeners. Use regular (or concentrated) plain unscented bleach.

Yes, if you store the bleach in the garage, it will last longer. Temperature makes a huge difference. You don't want it to freeze, however. The freezing point for 8.25% bleach is around 14ºF.
 

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I stocked up with HE concentrated bleach, it was on sale less than $1 for 64 ounces. I've been using it for a few weeks now and don't see any issues. no foaming at all anywhere. the most I ever added in one day was about a gallon. Is there a reason I should stop using it? Will I see forming if I shock (cya 40, 22k gallons, so ~3-4 gallons of this 8.25% bleach)

Thanks
 
Correct me if I am wrong, but every bleach I have seen has the HE sign on it. There maybe ones specifically formulated for HE, but all the bleach I have found has the HE logo, I think its just saying they can be used with HE machines. I am using some to slam my pool right now and have had no problems with it, just a regular concentrated 8.25 bleach.

Beens, thanks for the info. I didn't realize you could use both deal together! Gonna do that next time.
 
Chem geek, if optimal temps for storing 8.25 is around 72-74, should I move my bleach into my house? Its pretty hot here and our garage is pretty stuffy. Our average daily highs are in the mid 90s and lows around 78, I imagine my garage is staying in the 80s most of the time. Or should I even worry about it, I don't have a bulk supply yet, just about 8 gallons, which goes pretty fast when slamming.
 
You probably don't need to worry about it, but if you want to bring the bleach into the house that is OK to do. Just remember that the caps have a pressure release so some chlorine can sometimes outgas so you should put it somewhere with decent ventilation. On the other hand, I've got a bleach container (not used for the pool) under a sink and I've never noticed any metal getting oxidized.
 
chem geek said:
However, what you report seeing is completely different. You are measuring the expected FC a couple of hours after adding it (I assume this is after good circulation), but 24 hours later you have more FC with 8.25%. That makes no sense whatsoever. Once in the pool, the life of chlorine has nothing to do with its initial concentration. Yes, the warmer water temperature is very likely the reason the chlorine had more 24-hour loss. Roughly speaking, the chlorine reaction rates double every 13ºF so with a 5ºF increase in temperature the chlorine could get used up reacting with what is in the pool (or with a pool cover) 30% faster.
Click to expand...

Last night I had 3ppm. I lowered my PH from 7.8 to about 7.5 and about 30 min later added 64oz of 8.25% Today was hot and sunny all day. No clouds and no shade at all. Now, 24hr later - 4.5 ppm. How could I lose only 0.5ppm in 24 hours? (cya 35-40. 22-23k gallons. everything is in range)

I did not test for FC after adding this Clorox yesterday, is there a chance the concentration is higher than 8.25% (on label)?

How does different PH affect chlorine usage? Will chlorine be consumed a lot less when PH is 7.2-7.4 vs 7.8?

With 64oz of 12.5% I never had more than 3.5 ppm after 24 hours and some times I'd even have about 2-2.5 ppm

The temperatures are cooler now than in June-July when I used 12.5%, but still, loosing .5ppm when it's 85 outside and water temperature around 76(maybe more after today) just sounds unreal

The water is crystal clear.

Thanks

P.S. I have not used any products containing CYA in more than 2 months now, unless this Clorox has stabilizer in it (I could swear liquid shock target used to carry a few years back had stabilizer in it, but may be I was seeing things)
Also, my Clorox is HE, if that could affect the chlorine usage in any way. I have not had any foaming with it, not even when I added 2 bottles (128oz) at once
 
Chlorine is consumed less at lower pH than at higher pH, but that effect is mostly noticeable at shock levels (see this post). So you might have around 0.4 ppm FC less loss at the lower pH, but a lot of loss is still related to temperature and not just loss from sunlight. 76ºF is pretty cool for pool water so losing 0.5 ppm over 24 hours is possible. The more typical 2 ppm FC per day loss is from a combination of sunlight at higher pH -- 0.5 to 0.9 ppm loss (this assumes all loss is unbound chlorine and not chlorine bound to CYA and ignores any CYA shielding effect) -- and loss from temperature of 0.7 to 1.5 ppm depending on many factors.

If you keep track of this effect, let us know. Most especially if you just change the pH and track the loss at different pH, but the same temperature and amount of sunlight, that would be helpful confirmation of what I wrote in the post.
 

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