Need 2nd Opinion on % vs Volume vs $ calculation/assumptuion

[CarlD]

And what do these details add up to?

It still comes down to putting enough chlorine into your pool to make it sanitary. Is it going to matter if you think one gallon of LC is going to add 10.8ppm to 10,000 gallons when it only adds 10.3? What really matters is if the stuff is still good and relatively close to what it's supposed to be.

I'll bet not one person in 100 knows within 200 gallons how much water is in their pool. And if it's anything bigger than a donut, I'd guess that variation would be 500 gallons. I'll bet nobody here knows it that accurately. We know APPROXIMATELY how much water is in our pool. And, when it comes to shocking a pool, it doesn't REALLY matter if the pool is 19,000 gallons, 20,000 gallons, or 21,000 gallons. You can safely use 20,000 gallons for all your calculations.

So...where does the problem with this measure of concentration crop up? Where is the bleach calculator formula wrong? Why is it wrong? More importantly, is it wrong enough to matter? Or is it a good enough approximation?
(we know Isaac Newton's laws of Physics are fundamentally wrong and that Einstein's Relativity fixes those problems, but Newton's physics is STILL a good enough approximation to use to fly a probe past Pluto without resorting to Relativity. See my point?)

More importantly: Can YOU come up with a better method of determining if your bleach / liquid chlorine is still good?
By better I mean something a homeowner can practically implement, not something that needs a sterile lab with people in white coats.

Carl

[aylad]

This is bordering on China Shop material......the OP is satisfied with the information that he has. So if y'all want to continue the debate, please take it to the Shop!!

Janet

[CarlD]

Of course you are right.

Carl

[Sponge1971]

This is bordering on China Shop material......the OP is satisfied with the information that he has. So if y'all want to continue the debate, please take it to the Shop!!

Janet

- Does OP mean Original Poster? (just a wild guess...)

- I don't want to propogate any flaming but I do have more data to add to the whole purpose of this thread: to determine the most cost (and convenience) effective way to chlorinate my pool...ultimately anybody's pool. Briefly: I bought a 2.85liter jug of Walmart 4% for $1 !!! That's better than the original 5liters for $2. I'm going to 'Carl Test' it and compare it's $/ppm to the other's here... (I also sourced 7kg of 62% CalHypo, for ~$87...wow! that's steep, but massive Chlorine content...)

- I feel this discussion is valid to this master 'chlorine' thread, because (once this testing discrepancy can be settled) it will lead to a simple and cost effective method for 'poolies' to source their chlorine...and isn't that a cornerstone for BBB? 'simple' & 'cost effective'. If I may suggest...the future result of this discussion should result in an infromative, well written, descriptive 'sticky' for all poolies to find at the front of the 'cholrine' master thread. I'm certainly don't have the credentials...but I'm not totally helpless...and if anything, I cal play the roll of the layman lab rat.

- I'm just a FNG here, so let me know if I'm stepping out of line...but either way, I still appreciate the discussions we're having on the few threads I've posted to. My work mate 'poolies' just sigh and ask "who cares?!?" when I start discussing this thread. My BFF doesn't even test his pool anymore...he just backflushes, shocks and chucks in his weekly concoction. Ok...maybe that works...but it's certainly not the 'best way' to go. I appreciate yous guys are passionate about doing it the 'best way'...in the spirit of BBB. They look at me, like I have three heads, when I mention BBB to Them...that pretty much squahses any interesting/dynamic coffee break discussion.

[giroup01]

2,85L of 4% at $1/Liter = $0,09/ppm
7000g of 62% at $87 = $0,2/ppm

You would think the $1 bleach is quite inexpensive, but it's actually twice as expensive as the cal hypo from Trevi or the 65% stuff at Club Piscine.

The Costco HTH cal hypo, 22,7 kg for $94,99 is even more expensive at $0,06/ppm. You'd think they would be the cheapest.

[Sponge1971]

giroup01,

How are you coming up with X% of Yliters = $Z/ppm?

Is there some constant to describe how much ppmFC there is per %SodHyp?

[giroup01]

giroup01,

How are you coming up with X% of Yliters = $Z/ppm?

Is there some constant to describe how much ppmFC there is per %SodHyp?

0.9525
10.8% sodium hypo * 0.9525 = 10.3% available chlorine content.

[Sponge1971]

Here's a big azz wrench to throw in the works...

I just ran a 'Carl' on the jug of Walmart 4%.

1ml of Walmart 4% in my little 10liter 'pool' tests as 12.6ppmFC
(baseline tap water was 1.2ppmFC and sample read as 14ppmFC)

I'm fairly certain I didn't mess up. I will dump my 'pool' back into the 1liter measuring cup I used to fill it...in case I mis-counted. (even then...such a massive difference for +/- 1liter error?!?!?). I am 100% certain on the 1ml bleach sample. I ovefilled the syringe, bled the air, pushed out to exactly the 1ml line. I rinsed the syringe outside, then dumped it & flushed it. I stirred well, waited 10mins, re-stirred and multiple-flushed then pulled a 10ml sample.

If this method kinda points to %conc, then Walmart's supplier is pulling a fast one...to the consumer's benefit...which is w-a-y too suspicious. But...maybe it costs that particular supplier too much to dilute it down to 4%. -or- the supplier-du-jour only has 12% in their tanks...but, sometimes the other suppliers only have 4%...so Walmart has to mark for the least %conc. No doubt they have multiple sources for their store brand stuff. But I'd have to random sample all over the place to try and nail it down...forget it.

Anybody have anything to add?

UPDATE:
I just emptied 11 liters from the bucket. <sigh> That throws the math off...but that means the '%conc' must be even higher than 12%-ish. I just expanded the whole: 1ml in 11liters = 12.6ppm...up to my pool volume 20062liters for 1ppm change. I'm going to chuck 145ml of this stuff in and see what happens. My pool is 4ppm now. If it goes up to 5ppm, I guess it must be way more than 4%. True...I am only +/-0.5ppm resolution...but a little trinkle of 4% can't be worth much...the odds are it won't push me above 4ppm. We'll see....

[Sponge1971]

<sigh> a second update...
I wanted to work the angle on giroup01's suggestion of using CalHypo...
I have been searching around for info on whether CalHypo will increase my Calcium levels (which it will...so forget it)...and becuase I used "calcium hypochloride" in the search string...I ended up bouncing across a couple more "cost vs chlorine types" threads...and one driven by ChemGeek even. I'm sorry I missed them when I started this thread.
I don't want to flog a dead horse, and although I just skimmed the other posts (will get back to them...too late tonight) I suspect they are well and good for the cost vs chlorine I was trying to originally figure out.

Also...(not having read/searched other posts fully)...I also suspect Carl's post about determining PPM of the 'stuff' you have is the better place to continue the 'discussion' of the methodology and interpreting the results.

I don't know what other meat is left in this thread, after considering those other ones...I'm too tired now to suss it out.

Mod: if you feel this thread is now pointless and/or should be pmoved/closed/deleted...I trust your judgement. It's always best (and very hard) to keep like info (and usefull info) together...

[giroup01]

<sigh> a second update...
I wanted to work the angle on giroup01's suggestion of using CalHypo...
I have been searching around for info on whether CalHypo will increase my Calcium levels (which it will...so forget it)

Keep in mind that the pool will be opened about 4 months a year, and come October you'll drain it 2/3, whatever's left will be diluted by rain and melted snow, then you'll top it off in April with tap water.

So the increase in CH, whatever it is, is irrelevant.