# How to calculate cost per effective pool chlorine liquid vs powder

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• posted on April 27, 2012, 1:03 am
Q: How do 'you' calculate the cost per effective chlorine between liquid versus powder?
After googling, I find most answers say it fundamentally doesn't matter whether you use liquid (6% or 12%) chlorine or powder (56%-62% for dichlor or 90%-98% for trichlor, effective 85%).
The articles I found warn of other things (e.g., CYA isn't in the liquid & liquid raises the pH); but fundamentally they say the result is the same when it comes to ions of chlorination.
My problem is trying to compare the cost per effective pound of chlorine between liquids & solids.
Of course, costs vary greatly, so it's the EQUATION that matters. I can easily write the equation to compare the powders - but I'm having trouble comparing cost of powders versus liquids.
For example, to compare the cost for effective chlorine between two dichlors is easy. Given \$3.00 per pound of 56% dichlor versus \$3.33 per pound of 62% dichlor: FIRST CALCULATION: 56% dichlor at \$3.00/pound x 100/56 = \$5.36/pound effective chlorine SECOND CALCULATION: 62% dichlor at \$3.33/pound x 100/62 = \$5.37/pound effective chlorine COMPARISON: These two are about the same cost per pound of effective chlorine.
Likewise, to compare effective cost between trichlor and dichlor is, I think, (almost as) easy. For example, assume \$3.00 per pound of 56% dichlor versus \$3.33 per pound of 94% trichlor (84% effective chlorine): FIRST CALCULATION: 56% dichlor at \$3.00/pound x 100/56 = \$5.36/pound effective chlorine SECOND CALCULATION: 94% trichlor at \$3.33/pound x 100/84 = \$3.96/pound effective chlorine COMPARISON: The trichlor is vastly cheaper than the dichlor in this example.
Assuming the calculations above are using the correct equations, what I'd like to compare is the liquid versus the powders. But I can no longer simply compare percentages.
Q: What is the equation to compare effective chlorine prices for liquid vs powdered chlorine?
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<%-name%>
• posted on April 27, 2012, 1:51 am
wrote:

Yes you can. Liquid chlorine has a percentage of available chlorine just as the dry forms do. Bleach that you buy for laundry, etc, generally is 6%. Liquid chlorine sold for pools can be 12%. Whatever it is, the percentage is on the container.
So, let's say I have a gallon of 12% chlorine. A gallon of water weighs 8.3 pounds. The weight of the chlorine might be a tad different than pure water, but not enough to matter. So, you have 8.3 x 12% = 1lb of chlorine. Around here that gallon would cost about \$3.60.
Unless you have some unusual pricing, liquid chlorine is usually the least expensive form. As you already know, liq chlorine doesn't contain stabilizer. Which can be a good thing or bad thing depending on how much stabilizer is already in the pool.
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<%-name%>
• posted on April 27, 2012, 5:31 am
On Thu, 26 Apr 2012 18:51:40 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

Interesting math. That was what I was having the problem with. I didn't know if the percentage was by weight or by volume.
So, you're saying that 1 gallon of pool chorine is about 1 pound of chlorine. OK. That makes things simple to compare prices on.
I wonder if it matters if that pound of comparison chlorine is dichlor or trichlor?
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<%-name%>
• posted on April 27, 2012, 7:01 am
On Thu, 26 Apr 2012 18:51:40 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

I found some more information about how much chlorine is in a gallon of pool bleach. http://www.odysseymanufacturing.com/product_spec.htm http://www.troublefreepool.com/cost-comparison-of-chlorine-sources-t1859.html
Chlorine (sodium hypochlorite) 11.3% (10.8% weight % of available chlorine; 12.5% volume % of available chlorine aka Trade %) Lye (sodium hydroxide)=0.3% Salt (sodium chloride)=8.9% Watery.5%
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<%-name%>
• posted on April 27, 2012, 7:28 am
On Thu, 26 Apr 2012 18:51:40 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

I looked that up just now. http://www.troublefreepool.com/cost-comparison-of-chlorine-sources-t1859.html
1 gallon of 12.5% pool chlorine is 9.7 pounds (16% denser than water). 1 gallon of 6% bleach is 9.0 pounds (8% denser than water).
The math at that web site shows: 12.5% pool chlorine at \$3.25/gal calculates out to: \$3.25/gal x 1 gal/9.7# x 1/0.108 = \$3.10/# available chlorine
6% household chlorine at \$1.33/gal calculates out to: \$1.33/gal x 1 gal/9.0# x 1/0.057 = \$2.60/# available chlorine
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<%-name%>
• posted on April 27, 2012, 5:24 pm
On Fri, 27 Apr 2012 09:11:33 -0700, SMS wrote:

I agree. It all depends on the price and the % of available chlorine. I'm in the Silicon Valley - but I never heard of "Hasa". Googling, I find hasapool.com so I called the Hasa Northern CA office at 925-432-3866 who said their Redwood City office handles the valley 650-365-0441.
Apparently the smallest they sell is 36 cases of 4 gallons per case, with a minimum delivery charge.
But, I can find, at pool stores, the HASA "Sani-Clor / HASAChlor Sodium Hypochlorite" available locally at \$17 per case of 12% chlorine (\$4.25/ gallon).
The required math is \$17/case x 1 case/4 gallons x 1 gallon/9.7 pounds x 100 pounds solution /10.8 pounds chlorine = \$4.06/pound available chlorine.
Drat. That's lousy. :(
The down

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<%-name%>
• posted on April 29, 2012, 10:16 pm
On Fri, 27 Apr 2012 12:06:06 -0700, SMS wrote:

Nice find. It's a couple of towns over but I called Dave at 408-252-6280 (888-POOL-GUY) at 12361 South Saratoga-Sunnyvale Road, Saratoga California, 95070 whose normal price is \$18.40/4 gallons.
Using the math in the OP of this thread, it's still a bit high priced: \$18.40/4 gallons * 1 gallon/9.7 pounds * 0.108 = \$4.39/pound available chlorine
He's out of Chlorine this weekend, but they sell the 12.5% liquid chlorine (after the \$6 deposit) for \$21.44/8 gallons with the coupon from http://www.yourpoolguys.com/specials.html
\$21.44/8 gallons * 1 gallon/9.7 pounds * 0.108 = \$2.56/pound available chlorine
Now that's the first decent price I've seen in this entire thread!
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<%-name%>
• posted on April 27, 2012, 5:37 am
On Thu, 26 Apr 2012 19:50:55 -0700, SMS wrote:

I found this pool calculator: http://www.poolcalculator.com
Working backward, I played with the free chlorine (FC) parts per million (PPM) until I got even volumes (i.e., 1 gallon) and weights (i.e., 1 pound).
Here are the equivalencies that calculator came up with: 1 gallon 6% bleach ==> 1.6ppm FC 1 pound dichlor ==> 1.7ppm FC
1 gallon 12% bleach ==> 3.2ppm FC 1 pound trichlor ==> 2.9ppm FC
Given that, it looks like the following may be the equivalency I seek: 1 pound of dichlor = 1g of household bleach = 1/2g of pool bleach 1 pound of trichlor = 1g of pool bleach = 2g of household bleach
Do these seem reasonable to you for comparisons of liquid vs powder?
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<%-name%>
• posted on April 27, 2012, 8:29 am
I googled for local (Silicon Valley) prices so that I could update the calculations. 1. Lowes 85% available Cl TriChlor = \$75/35 pounds 2. Lowes 56% available Cl DiChlor = \$70/22.5 pounds 3. PoolSupplies 73% available Cl Calcium HypoChlorite = \$160/48 pounds 4. Leslies 35% available Cl Lithium HypoChlorite \$165.36/24 pounds 5. Lowes 12% chlorine = \$6.90/2 gallons 6. Safeway 6% household bleach = \$3.89/1.42 gallons
Redoing those calculations with my new price data above, we get: 1. Trichlor tabs -> \$2.14 / 0.850 = \$2.52 (need to account for Washing Soda to adjust pH) 2. Dichlor granules -> \$3.11 / 0.560 = \$5.55 (need to account for Washing Soda to adjust pH) 3. 73% Cal-Hypo granules -> \$3.33 / 0.730 = \$4.57 4. Lithium Hypochlorite granules -> \$6.89/ 0.350 = \$19.69 5. 12.5% Chlorinating Liquid -> \$3.45/gallon x 1gallon/9.7pounds x 1/0.108%wt = \$0.356 / 0.108 = \$3.29 6. 6% Bleach -> \$2.74/gallon x 1gallon/9.0pounds x 1/0.057%wt =\$0.304 / 0.057 = \$5.34
Ordering by price per pound of available chlorine, we get: a) 85% available trichlor tabs at \$2.52/pound available chlorine b) 12.5% chlorinating liquid at \$3.29/pound available chlorine c) 73% CalHypo granules at \$4.57/pound available chlorine d) 6% bleach at \$5.34/pound available chlorine e) 56% available dichlor granules at \$5.55/pound available chlorine f) 35% available Lithium HypoChlorite at \$19.69/pound available chlorine
Q: Do these numbers look reasonable? Q: Can you get any of these chemicals for substantially cheaper (including all costs) online?
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<%-name%>
• posted on April 27, 2012, 6:58 pm
wrote:

I would have thought that liquid chlorine would be the least expensive. But since you brought this up I too did a bit of calculating. And it looks like trichlor is substantially less than liquid chlorine. Costco for example has it for about \$2 a pound. So, just from the standpoint of the most chlorine for the least money, trichlor is it. But as you know there are other differences that could make one better than the other for other reasons.
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<%-name%>
• posted on April 30, 2012, 3:29 am
On Fri, 27 Apr 2012 17:43:39 -0700, SMS wrote:

I was at the Costco on Coleman last week.
They have three chlorine products: 1. Bleach: \$9/182 fl oz x 3 bottles, nominal 6% = \$2.11/gallon 2. Trichlor: \$84.79/40 pounds, 94.05%, 84.65% available Cl = \$2.12/pound 3. Dichlor: \$55/24 one-pound packets = \$2.29/pound (but wait!)
The first two are easy to calculate the cost for available chlorine: 1. Bleach: \$9/546oz * 128oz/gal * 1gal/9.0pounds * 100pounds/5.7pounds \$4.11/pound of available Cl
2. Trichlor: \$84.79/40 pounds * 100/84.65 pounds = \$2.50/pound of available Cl
It turns out the dichlor at Costco is a rip off.
It's Costco item #175121, "aqua chem Shock Plus 4 in 1 pool shock 24 pack, EPA REG No 67262-27 telephone 800-252-7665.
It doesn't list the available chlorine. Wanna know why? Because it is very very very low!
Looking up the patent number on the box of Costco dichlor, the MSDS for "Pool Time ® Shock Plus 4-IN-1 POOL SHOCK" simply says it contains two trade secrets: 1. TRADE SECRET 001 = 5% to 15% 2. TRADE SECRET 016 = 1% to 10% 2005-01-01) Calling Customer Service on Friday, 8am to 6pm EST 800-859-7946, they wouldn't tell me what was in it.
The box has a patent number on it, "US Patent no. 5,670,059". Googling for that, we find the four ingredients: 60% sodium dichloro-s-triazinetrione, 20% sodium persulfate, 10% sodium tetraborate, and 10% aluminum sulfate (an additional clarifying agent)."
So, what you 'think' you're getting is pool shock - but what you're actually getting is a bunch of filler that makes the available chlorine next to nothing (so low they won't even say what it is!).
Here's the MSDS: http://www.homedepot.com/catalog/pdfImages/88/887cfccb- d500-496b-96ae-21133f3ec5c4.pdf
And here's the patent: http://patents.justia.com/1997/05670059.html
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<%-name%>
• posted on April 30, 2012, 3:38 am
On Mon, 30 Apr 2012 03:29:01 +0000, Dakar F. wrote:

Someone should call the manufacturer to find what the real available chlorine is for the Costco item #175121.
The box says "aqua chem Shock Plus 4 in 1 pool shock 24 pack (EPA REG No 67262-27) and it lists two phone numbers: 800-859-7946 & 800-252-7665
Given the equation for 'normal' dichlor, if the Costco was 'normal' stuff, this would be the equation (i.e., 85% dichlor dihydrate which is 55% available chlorine): a) \$55/24 pound x 100/55 = \$4.17/pound of available Cl
But, given the Costco dichlor is only 58.2% by weight, this is the BEST it can be for available chlorine! b) \$55/24 pounds x 100/55 x 85/58.2 = \$6.09/pound of available Cl
Given the manufacturer's duplicity in labeling the box, I doubt the chlorine level of this so-called shock is even as much as that.
Note: It's not even classified as an oxidant by the DOT because it's so diluted (it says so right in the patent description!).
Moral of the story: Unless someone who knows more than I says otherwise, my personal assumption is that the Costco dichlor dihydrate is a rip off!
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<%-name%>
• posted on April 30, 2012, 2:59 pm
On Mon, 30 Apr 2012 03:38:52 +0000 (UTC), Dakar F. wrote:

I'm on the phone with the "Biolab pool and spa care products pro division" so I'll take notes.
Calling: 800-859-7946, press 1 for Biolab Ask for technical support. Got Scott in Technical Solutions He asked for the 'product code' which is "22112AQU" I asked what's the available chlorine. He said 36%.
We then talked a bit about the box and he said the Marketing guys own the printing on the box and they sometimes put the available chlorine and sometimes don't.
The parent company is "ChemTura BioLab" who owns the three brands under the "Recreational Water Products" umbrella (which are chemically identical), those divisions being AquaChem, PoolTime, and SpaTime.
He said PoolTime goes to Home Depot who wants to differentiate from Lowes. AquaChem goes to Lowes and Walmart (and sometimes CostCo when they can get in the door).
He said it's a class 1 oxidizer. And he confirmed it's a dichlor dihydrate.
He said the purpose of the ingredients are: - 60% sodium dichloro-s-triazinetrione (oxidizer, 36% available chlorine) - 20% sodium persulfate (oxidize the combined chlorines) - 10% sodium tetraborate (water softener) - 10% aluminum sulfate (clarifier)
I then called 800-252-7665 & got Jordan in Customer Care in Atlanta Georgia. He confirmed the company tree and said the 4-in-1 didn't refer to ingredients, but it referred to four benefits, namely: 1. algaecide & bacteriacide 2. reduce contaminants 3. water softener 4. clarifier
I complained that the 36% is rather low for an oxidant and he said people don't buy it for oxidizing. They buy it because they have a party and they need to raise the chlorine level immediately and he said this stuff dissolves quickly (maybe the glycoluril?).
Anyway, my recommendation is to NEVER buy any dichlor dihydrate that doesn't say it's a dihydrate and that doesn't state the available chlorine.
You can assume 36% if it doesn't state how much is there!
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<%-name%>
• posted on April 30, 2012, 12:28 pm

The product didn't say it was chlorine. It said it was SHOCK. There are other forms of shock that do not use chlorine. One of them is sodium persulfate, which is a strong oxidizer. So it looks like this product uses a combo of dichlor and sodium persulfate. Whether that is a good thing or bad thing probably depends on a lot of factors, but the point is that the product is not necessarily a rip off and certainly not deceptive.

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<%-name%>
• posted on April 30, 2012, 7:43 pm
On Mon, 30 Apr 2012 05:28:55 -0700, snipped-for-privacy@optonline.net wrote:

You may be right (I don't know).
But I'd have to ask how come all the other manufacturers list their available chlorine on 'their' shock... yet pooltime/aquachem forgot to list it on their shock.
Do you think it's because they didn't have the room?
Or because it's so low (compared to the others) that they didn't want to say it?
I don't know the answer. But I suspect it.
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<%-name%>
• posted on April 30, 2012, 8:43 pm

Go look at a container of potassium monopersulfate shock and you won't see the available chlorine listed either, because there isn't any.

No, they did it because the chlorine in their product is only ONE component of the shock product. If they listed the chlorine, while it would be interesting, it would just confuse people like you that are just comparing chlorine and not how much shock they are getting.

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<%-name%>
• posted on May 1, 2012, 5:11 pm
On Mon, 30 Apr 2012 13:43:13 -0700, snipped-for-privacy@optonline.net wrote:

Ok. Good point.
In the case of the Costco/Lowes/Walmart AquaChem 4-in-1 shock, you're saying that some of the 'other' ingredients are also sanitizers - so just putting the low available chlorine of 36% would confuse people because those additional sanitizers don't contain chlorine yet they kill bacteria just as well. OK. I see your point.
However ... guess what?
The very same company sells PoolTime specifically branded for Home Depot to compete with Lowes. Notice, this same company pulls the same missing- information trick on their Home Depot Pooltime 40 lb. Chlorinating Granules (Model #22891PTM, Store SKU # 912970) at \$119.00.
As in the Costco case, you have to call the (same) company to find out that it's 56% available chlorine because they don't list it on the package. And, in this case, it's the ONLY ingredient! (other than inert ingredients)
So, in this case, it can't be that they are trying not to confuse us! See for yourself!
Look at the zoomed-in photograph in this Home Depot link: - http://www.homedepot.com/h_d1/N-5yc1v/R-202245637/h_d2/ProductDisplay? catalogId053&langId=-1&keyword=chlorine&storeId051
I've been to the Home Depot and there is NOTHING on the label that says the available chlorine!
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<%-name%>
• posted on May 1, 2012, 5:15 pm
On Tue, 01 May 2012 08:14:15 -0700, SMS wrote:

I agree with you. From now on, I'm going to that Saratoga store you pointed me to for my liquid chlorine (only after printing the coupon though)!
I like the BBB method which we can buy at Safeway or Target: - Bleach: sanitizer - Baking soda: pH - Borax: buffer http://www.troublefreepool.com/the-bbb-method-f54.html
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<%-name%>
• posted on May 1, 2012, 5:39 pm

It's more like BA, bleach and hydrochloric acid. Bleach has a high PH, so you're not going to balance it with baking soda, which is another base.
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<%-name%>
• posted on May 2, 2012, 3:36 am
On Tue, 1 May 2012 10:39:34 -0700 (PDT), " snipped-for-privacy@optonline.net"

Baking soda is really a buffer (raises total alkalinity more than just the pH), but you're right, you're not taking the pH down with baking soda.
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<%-name%>

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