On Thu, 4 Aug 2016 17:05:39 -0700 (PDT), trader_4 wrote:
I was diluting 2 parts HASA with 1 part water but I was just guessing based
on a pool calculator which said that 1 gallon of 6% household bleach gave a
given pool 1.6 parts per million free chlorine as compared to a gallon of
HASA 12.5% pool chlorine which gave that same pool 3.2 parts per million of
Since 1.6 goes into 3.2 twice, I was mixing 2 parts of HASA to one part
water, but I wasn't sure if that was correct.
Do you think it should be 1:1 HASA to water or 2:1 HASA to water to mimic
On Thursday, August 4, 2016 at 9:15:26 PM UTC-4, David Jensen wrote:
Look at it this way. Whatever good stuff that is in that gallon,
if you add water so it's two gallons, then you'll have the same
good stuff in twice as much water, making it half the strength
that it was.
On Thu, 04 Aug 2016 19:55:08 -0400, firstname.lastname@example.org wrote:
When I tried to figure out the answer on my own, I found that the percent
is different whether it's a percent by volume or a percent by weight or
even a percent by "trade percent" (whatever that is).
All these different ways of measuring percent are confusing to me which is
why I asked the question.
This reference said the MSDS for "Clorox Regular Bleach" says it's 6.15%
But that still doesn't tell me which percent that is (by weight? by volume?
by available ppm of sodium hypochlorite?) so the numbers can be off by a
huge amount since I'd be comparing apples to oranges to bananas (weight
versus volume versus reactivity).
On Fri, 05 Aug 2016 22:47:54 -0400, email@example.com wrote:
No. It's actually true.
It's a chemistry thing.
But I forget why.
I took chemistry so long ago, that I forget why, but the chem teacher
drilled the decomposition concept into us at the time, just as he did redox
reactions and intimate knowledge of s and p orbitals. :)
I'll look it up, but, I'm positive that the stronger the hypochlorite
solution, the less stable it is - but I could also be wrong.
Googling, Wikipedia mentions that household bleach has sodium hydroxide
added to make the solution more basic, which also slows down
" Household bleach is, in general, a solution containing 3–8% sodium
hypochlorite and 0.01–0.05% sodium hydroxide; the sodium hydroxide is used
to slow the decomposition of sodium hypochlorite into sodium chloride and
Further googling finds this CDC article
which says "Hypochlorite solutions in tap water at a pH >8 stored at room
temperature (23ºC) in closed, opaque plastic containers can lose up to
40%–50% of their free available chlorine level over 1 month."
Luckily, this stops after 30 days (why, I don't know): "Sodium hypochlorite
solution does not decompose after 30 days when stored in a closed brown
But I'll look it up further so that I can back up what I said.
On Sat, 6 Aug 2016 09:42:55 -0300, David Jensen wrote:
Turns out the keywords were "stability" and "decomposition".
Add those to the search, and the information amount is astounding!
This PDF on stability says outright what I remember from chemistry:
"Sodium hypochlorite at higher concentrations will have a faster
decomposition rate. Conversely sodium hypochlorite at lower concentrations
will have a slower decomposition rate."
Unfortunately, it also says that the metals in my tap water diluent will
increase the decomposition rate.
Apparently there are five things that affect decomposition rate:
4) Impurities such as magnesium and calcium
1. Dilute bleach lasts longer
2. Colder bleach lasts longer
3. Higher pH lasts longer
4. Distilled water helps it last longer
5. Dark areas help it last longer
This one goes into the rate math, which is 4 or 5 times faster:
"Without salt, 200 gpl available chlorine sodium hypochlorite will
decompose 4 times faster than 100 gpl product when stored at the same
temperature. With the normal amount of salt produced during the reaction,
(Cl2 + 2NaOH = NaOCl + NaCl + H2O), the decomposition rate is a factor of 5
greater for the 200 gpl product versus the 100 gpl product at the same
Here's a guy who studied the shelf life of 5% bleach:
5,00% at day 0
4,96% at day 30
4,77% at day 60
4,43% at day 90
4,32% at day 120
4,26% at day 150
4,07% at day 180
3,67% at day 210
3,51% at day 240
3,23% at day 270
3,16% at day 300
2,70% at day 330
2,36% at day 360
2,19% at day 390
1,84% at day 420
1,58% at day 450
1,32% at day 480
1,14% at day 510
Roughly, it's half of what it was after a year in storage.
It's still pretty good at about 3 months to 6 months.
On Thursday, August 4, 2016 at 9:19:18 PM UTC-4, David Jensen wrote:
It doesn't really matter for your purposes if it's by weight or by
volume. If you add water by weight to double the amount or by
volume to double the amount, you're going to wind up with bleach
that is half the strength. There are some negligible differences,
but we're talking household bleach here, right?
On Fri, 5 Aug 2016 00:29:05 -0700 (PDT), trader_4 wrote:
I took your advice and simply halved it.
Halving the HASA turned 8 gallons of 12.5% "trade percentage" (sodium
hypochlorite by weight I think?) into 16 gallons of household bleach of
roughly 6% to 10% by volume (I think).
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