Best Places to Buy Liquid Chlorine

[Gary Davis]

I just purchased 10 gals LC via online at Walmart. I picked it up and the mfg. Date was 8/11/22 - just over 2 wks old. So it appears that WM is still purchasing LC. This is Pool Essentials 10%.

Who knew there was a thread for chlorine prices, as my liquid chlorine distributor recently raised his prices to $29.33/4 for the 12.5% bleach ($7.33/gallon).
(I like the hasa approach because it ends up being much better for the environment than the store bought packaged bleach ends up as.)

In another thread (over here) I had just this week previously linked to current 10% Walmart (Pool Essentials) and 10% Home Depot (HDX, Kem-Tek & Pool Essentials) prices of roughly $5/gallon. I only found the date code wiki recently so I'll check what I got from each.

Found tons of weight:volume:trade% math threads
1. Weight Verses Trade- Understanding Chlorine Concentrations in Different Sources
2. Bleach concentration per unit volume and other calculations
3. Measuring liquid chlorine/bleach by weight
4. How to calculate cost per effective chlorine liquid v powder
5. Cost Comparison of Chlorine Sources

Ran the two calculations (EDIT: The 10% values are corrected as per the doublecheck kindly performed by ccbill below!)
1. 10% Walmart & HD = ~$5/gal x 1gal/9.4# x 1/8.77% available chlorine by weight = ~$0.06 per pound of available chlorine
2. 12.5% Hasa = ~$7/gal x 1gal/9.7# x 1/10.78% available chlorine by weight = ~$0.07 per pound of available chlorine

Well, there it is.
Obviously, the equation will remain the same for everyone but the price paid per gallon will change for each of us and over time.

I don't use pucks or powder, but if someone needs the solids calculation, the formula is apparently
3. Solids: $x/y# x 1/z% available chlorine by weight = price per pound of available chlorine
Where x is the cost of the solid and y is the number of pounds you bought and z is the available chlorine percentage printed on the label.

 

[HeyEng]

Our local Atwoods still have it in stock (526 one gallon bottles as indicated online) at $3.99/gallon. It also shows a 5 gallon limit for purchase, but I am not sure if they are enforcing that or not.

 

[thefloatqueen]

It’s stupid expensive here if I buy from our local Kroger (because convenience lol). An 81 oz bottle of 7.5% bleach is $4.49 and 121 oz 7.5% is $5.79. Obviously, I buy the big bottle when they are in stock! Both are just regular Kroger brand bleach. They do have sales often, though.

 

[ccbill]

1. Weight Verses Trade- Understanding Chlorine Concentrations in Different Sources
...
DOUBLEEDIT: Ran the two calculations
1. 10% Walmart & HD = ~$5/gal x 1gal/9.0# x 1/5.7% available chlorine by weight = ~$0.10 per pound of available chlorine
...

Are your calcs correct? The table in that wiki page says 8.77% available chlorine for 10% trade. Making the HD 10% a better buy. And the HD SDS says it is 10% by weight

 

[Gary Davis]

Are your calcs correct? The table in that wiki page says 8.77% available chlorine for 10% trade. Making the HD 10% a better buy. And the HD SDS says it is 10% by weight

View attachment 450649

Thank you for checking the numbers and for asking that clarifying question because accuracy is what matters.
I got the numbers from a chem_geek post, where I gauged that Richard Falk seemed to know this stuff pretty well.

chem geek:
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%
Water 79.5%

But maybe I copied chem_geek's numbers wrong? Or maybe I misunderstood his numbers.
He sure seemed like a reliable guy - and I can generally tell if someone knows what they're talking about.

Let me go and find the numbers again (I have to run the same search again so I should have linked to it the first time).
OK. Here is where I found those numbers where it's important that he recommends 12.5% but not higher (for storage:degradation reasons).

chem geek said:
12.25% Trade which is % Available Chlorine by volume is 10.78% Available Chlorine (by weight) ... The divisor in those equations calculating pounds of available chlorine are "% Available Chlorine (by weight)".

chem geek said:
While chlorinating liquid is usually sold by Trade %, the percentage for regular bleach is usually weight % of product (i.e. sodium hypochlorite) so 8.25% bleach (weight % of sodium hypochlorite) is 7.86% Available Chlorine (by weight) and assuming a 1.10 g/ml density this is 9.08% Trade (% Available Chlorine by volume).

The chem_geek numbers are listed above, but I think I found a place where the error may be by reading the entire referenced thread.

• liquid chlorine: $cost/gallon x 1gallon/9.7pounds x 1/10.78% available chlorine (by weight) = price per pound of available chlorine
• liquid bleach: $cost/gallon x 1gallon/9.0pounds x 1/5.7% available chlorine (by weight) = price per pound of available chlorine
• solids: $cost/pound x 1/xx% available chlorine (by weight) = price per pound of available chlorine

I had assumed the "liquid bleach" 9 pounds and 5.7% was for the 10% bleach but those seem to be for the 6% bleach when went back and I read the whole thread.
If I take the 8.77% you found, I guess that means the overall set of equations for general use would be the following.

Liquids

• 12.25% Trade% liquid chlorine: $cost/gallon x 1gallon/9.7pounds x 1/10.78% available chlorine (by weight) = price per pound of available chlorine
• 10% Trade% liquid chlorine: $cost/gallon x 1gallon/9.4pounds x 1/8.77% available chlorine (by weight) = price per pound of available chlorine
• 8.25% Trade% liquid chlorine: $cost/gallon x 1gallon/9.0pounds x 1/7.86% available chlorine (by weight) = price per pound of available chlorine
• 6% Weight% laundry bleach: $cost/gallon x 1gallon/9.0pounds x 1/5.71% available chlorine (by weight) = price per pound of available chlorine

Solids

• Sodium Dichloro-s-Triazinetrione, anhydrous at 99% by weight (available chlorine is 64% by weight, or as listed on the package):
  • $cost/pound x 100 pounds solid/64 pounds available chlorine = price per pound of available chlorine
• Sodium Dichloro-s-Triazinetrione dihydrate at 99% by weight (available chlorine is 55% by weight, or as listed on the package)
  • $cost/pound x 100 pounds solid/55 pounds available chlorine = price per pound of available chlorine
  • This dichlor is sometimes listed as Sodium Dichloro-s-Triazinetrione, typically 85% by weight with 14% locked-up water, but the available chlorine is 55%
• Trichlor aka trichloroisocyanuric acid or trichloro-s-triazinetrione at varying % by weight (available chlorine varies by weight as listed on the package):
  • $cost/pound x 100 pounds solid/{90,85,84.65} pounds available chlorine = price per pound of available chlorine
    • Home Depot & Leslie's Pool 99% trichlor is listed as 90% available chlorine
    • Lowes 95% trichlor is listed as 85% available chlorine
    • Costco 94.05% trichlor is listed as 84.65% available chlorine
• Aqua Chem Shock Plus 4 in 1 pool shock, Costco item #175121, 24 pack (where available chlorine is 36% but it is not listed on the package):
  • $cost/pound x 100 pounds solid/36 pounds available chlorine = price per pound of available chlorine

Re: Bleach concentration per unit volume and other calculations

Weight % Available Chlorine = Trade % / Specific Gravity
Trade % = Weight % Available Chlorine * Specific Gravity

Weight % NaOCl = Weight % Available Chlorine * (NaOCl g/mole) / (Cl₂ g/mole)
Weight % Available Chlorine = Weight % NaOCl * (Cl₂ g/mole) / (NaOCl g/mole)

Weight % NaOCl = (Trade % / Specific Gravity) * (NaOCl g/mole) / (Cl₂ g/mole)
Trade % = Weight % NaOCl * Specific Gravity * (Cl₂ g/mole) / (NaOCl g/mole)

NaOCl g/mole = 74.442
Cl₂ g/mole = 70.906

Though bleach generally has the Weight % NaOCl in the ingredients and sometimes (for Clorox unscented, for example) lists the "% Available Chlorine", chlorinating liquid is most often sold by Trade %. The Trade % is technically the Volume % Available Chlorine and therefore is the only quantity that exactly matches its number with ppm in the pool as with 1 gallon in 10,000 gallons of 12.5% chlorinating liquid produces 12.5 ppm FC.

Their column of "% Active Chlorine (w/w)" is more commonly known as "% Available Chlorine" and is a weight % while their text before the table refers to "% Active Chlorine (w/v)" which is incorrect. The column "Active Chlorine (g/l)" is more commonly expressed as the Volume % Available Chlorine and is more commonly known as Trade %. It is their % Active Chlorine (w/w) column multiplied by the Average Density column (which gives you "100% * g Cl₂ / ml product" so you can take their "Active Chlorine (g/l)" and divide that by 10.

The reason the density is not linearly increasing with concentration of chlorine is that the density is also dependent on the amount of "excess lye" (sodium hydroxide) in the product and that does not vary linearly with concentration since it is instead designed to produce the needed pH that results in greater stability for the specific concentration of chlorine. This can vary by manufacturer.

In my spreadsheet from which The Pool Calculator was based (in part), I certain densities based on MSDS data from bleaches and on spec sheets for chlorinating liquid. Let's see how my assumptions lined up with the Solvay Chemicals table:

[EDIT] The first three Trade % numbers below were corrected as they were originally in error. [END-EDIT]

Product ........................... Weight % NaOCl . % Available Chlorine . Trade % . my Density . Solvay Density
5% Bleach ............................... 5.00% ................. 4.76% ................ 5.09% ...... 1.07 ............. 1.070
6% Bleach ............................... 6.00% ................. 5.71% ................ 6.17% ...... 1.08 ............. 1.085
8% Bleach ............................... 8.00% ................. 7.62% ................ 8.38% ...... 1.10 ............. 1.117
10% Chlorinating Liquid ......... 9.21% .................. 8.77% .............. 10.00% ...... 1.14 ............. 1.136
12.5% Chlorinating Liquid .... 11.32% ................ 10.78% .............. 12.50% ...... 1.16 ............. 1.175

The Odyssey Manufacturing spec for 12.5% (trade) gives a specific gravity of 1.164 while the Solvay table gives 1.172 (interpolating) so density does vary some by specific product.

So if you use Trade % for the chlorinating liquid presumed to be 10% or higher, then The Pool Calculator is closer than your calculation that assumed that chlorinating liquid was quoted as Weight % NaOCl. On the other hand, I've seen a lot of chlorinating liquid with what one would think is the Trade % instead listed as Weight % NaOCl in the ingredients. Since the product is shipped at a higher % since it is presumed to degrade, this is all approximate anyway, especially for chlorinating liquid (typical bleach degrades more slowly).

The missing number is the weight of the 10% Trade where the weight of the other liquids seems to have come from here.

chem geek said:
12.5% Chlorinating Liquid ... $3.25 for 1 gallon from my local pool store (9.7 pounds -- product is 16% denser than water) so that's $0.336 per pound
6% Bleach ... $1 for 96 ounces (6.75 pounds -- product is 8% denser than water and 96/128th of a gallon) so that's $0.15 per pound

Unfortunately, we need BOTH numbers, the percent and the weight where most of the Richard Falk charts are the percent.

chem geek:
5.25% Bleach 5.0% (also adds 0.82 ppm extra salt)
6.0% Bleach 5.7% (also adds 0.82 ppm extra salt)
10.0% Chlorinating Liquid 8.8% (also adds 0.82 ppm extra salt)
12.5% Chlorinating Liquid 10.8% (also adds 0.82 ppm extra salt)
Lithium Hypochlorite 35.2% (also adds 0.76 ppm extra salt)
48% Cal-Hypo 47.6% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt?)
Dichlor Dihydrate 55.4% (also adds 0.91 ppm Cyanruic Acid, CYA)
Dichlor Anhydrous 64.5% (also adds 0.91 ppm Cyanruic Acid, CYA)
65% Cal-Hypo 64.5% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt)
73% Cal-Hypo 72.4% (also adds 0.71 ppm Calcium Hardness, CH; 0.2 ppm extra salt)
Trichlor Tabs/Pucks 91.5% (also adds 0.61 ppm Cyanuric Acid, CYA)
Chlorine Gas 100.0%

However, if only I understood this post below better from chem_geek, I could probably figure out the weight for the 10% Trade myself.

Weight % Available Chlorine = Trade % / Specific Gravity
Trade % = Weight % Available Chlorine * Specific Gravity

Weight % NaOCl = Weight % Available Chlorine * (NaOCl g/mole) / (Cl₂ g/mole)
Weight % Available Chlorine = Weight % NaOCl * (Cl₂ g/mole) / (NaOCl g/mole)

Weight % NaOCl = (Trade % / Specific Gravity) * (NaOCl g/mole) / (Cl₂ g/mole)
Trade % = Weight % NaOCl * Specific Gravity * (Cl₂ g/mole) / (NaOCl g/mole)

NaOCl g/mole = 74.442
Cl₂ g/mole = 70.906

EDIT: Found the missing numbers and I inserted them above, in red.

 

[tcat]

...or just convert to SWG and never have to buy chlorine again! Fairly easy DIY.

 

[Gary Davis]

...or just convert to SWG and never have to buy chlorine again! Fairly easy DIY.

We have to keep in mind the title of this thread is the best places to obtain chlorine at a good price, where one could argue whether the SWG plays a role in the answer.
I guess we could argue that part of being the "best" for a commodity is the "best price" (which is where the economics of SWG comes into the equation, albeit not directly but indirectly) but the SWG has a startup cost that the bleach does not (while the SWG presumably has an overall cost saving, we can hope, over its lifespan).

What's the average cost for SWG equipment and maintenance and how long is the break-even time between these two basic scenarios?
1. Average 10K or 20K gallon plaster pool owner applies liquid chlorine for five years of pool ownership, versus
2. Average 10K or 20K gallon plaster pool owner converts to SWG on day one and maintains it for five years

What's roughly the break-even time period for most people between the two common scenarios?
For example, can you break even in one year? Five years? Ten years? Twenty years?

I found this thread from Richard Falk on the economics of SWG payback periods (which depends GREATLY on the price of electricity, which, for me, is extremely high).

 

[Newdude]

What's the average cost for SWG equipment and maintenance and how long is the break-even time between these two scenarios?

I did maths for 19.5k gallons a while back :
(25k will be more in your favor because you'll need more of those expensive gallons with LC and also more of the cheaper SWG ones)


$6 gallon of LC : $1.16 per FC
$4 gallon of LC : $0.66 per FC

^^^^^ depending on sales you will land somewhere between these two.

(The expensive 2X rated SWG) IC40 : $ 0.42 per FC. There are cheaper models for even more savings

 

[Newdude]

Here was another one for a 20k pool where a poster had 3 stores prices and wanted to compare.

HD = $0.90 per fc
Pap= $0.94 per fc
Wm= $1.20 per fc.

Pentair IC40 (2X rated for you) $1509 today

Self install = $0.43 per fc
Pro install (generous + $500) = $0.57 per fc

^^^^ all the above for 20k gallon OP pool / location/ current prices. No taxes added as it's a wash paying over and over on jugs or one time on a SWG.

 

[tcat]

The main reason I switched to SWG this year was availability of chlorine here (Austin), and price increase of it. My cost to switch was $1000 (DIY), for a 40k gallon cell with 7 year warranty, $500 replacement cell cost in 5-7 years. The cost was well worth avoiding the cost, search, and trips finding jugs. Was able to convert my Stenner feed from chlorine to acid, so maintenance is almost zero. I never really did the math, but in the long run, hopefully saving money.

My system: Circulpool Edge-40, $1250 today, replacement cells $600, 7 yr warranty
Other: IC40 $1650, cell $990, 60 day warranty

 

[geh]

The main reason I switched to SWG this year was availability of chlorine here (Austin), and price increase of it. My cost to switch was $1000 (DIY), for a 40k gallon cell with 7 year warranty, $500 replacement cell cost in 5-7 years. The cost was well worth avoiding the cost, search, and trips finding jugs. Was able to convert my Stenner feed from chlorine to acid, so maintenance is almost zero. I never really did the math, but in the long run, hopefully saving money.

My system: Circulpool Edge-40, $1250 today, replacement cells $600, 7 yr warranty
Other: IC40 $1650, cell $990, 60 day warranty

I too switched to SWG this year due to the major price increases of LC and also the lack of fresh product. I was getting about 50% potency of 12.5% LC at $7.00/gal, thus $14.00/gal in real life. My SWG is generating pure fresh chlorine, my chlorine levels are stable and better than when I was dumping LC into the pool daily, and the only time I added LC was yesterday, and that was only because I had cracked open one of my last LC gallons to clean a spot algae out of the grout of my deck, and just dumped the remaining three quarts into the pool to get rid of the LC, not because I needed it at all.

I think economically its the better option now over LC, and hassle free. The only thing I have to add now is some muriatic acid every few days, and its so predictable, I can probably just add the same amount of MA without testing. Completely hassle free and my chlorine levels are always excellent. I haven't been to my local pool store in over a month, whereas it was about twice a week before.

 

[IceShadow]

@Gary Davis @Newdude - did you guys know PoolMath has a bleach price calculator? Under the three line menu, "Bleach $ Calculator" - it takes strength into account.

 

[Gary Davis]

Are your calcs correct?

Found it!
After scores upon scores of searches, I read almost every post, if not every post from Richard Falk (aka chem geek) and finally found it here.

chem geek:
I get 12.5% chlorinating liquid from Herb's Pool Service for $15.80 for 4 gallons so at 9.7 pounds per gallon that's $0.407 per pound. Your Home Depot calculation is not correct since 10% chlorinating liquid is less dense than 12.5% and probably weighs 9.4 pounds per gallon so would be $0.366 per pound. Also, you divided by 0.0808 instead of the correct factor of 0.088. So the right calculations give:

10% Chlorinating Liquid ... $3.44 for 1 gallon from HD (9.4 pounds -- product is 13% denser than water) so that's $0.366 per pound
10% Chlorinating Liquid . $0.366 / 0.088 = $4.16

12.5% Chlorinating Liquid ... $15.80/4 = $3.95 for 1 gallon at Herb's (9.7 pound -- product is 16% denser than water) so that's $0.407 per pound
12.5% Chlorinating Liquid . $0.407 / 0.108 = $3.77

Great Value Linen Bleach at Walmart might be 8.25% bleach though I am not sure, but it's $2.98 for 121 fluid ounces which for 12 ppm FC in 10,000 gallons is $4.45.

I've updated the calculations in this post above so that anyone reading this from front to back won't have to worry about the later corrections.
Thank you @ccbill very much for finding my error!

Whether or not someone uses a calculator, it's ALWAYS a good idea to know what the components of the equation are and, more importantly, how they relate to each other as that shows an understanding of the chemistry, and not just the ability to plug the numbers into a calculator application.

Knowing the equation is the part that takes intelligence as running the math is nothing more than simple arithmetic after that.

However, what I found interesting was that the 12.5% Trade used to be (much) cheaper than the Home Depot & Walmart 10% Trade, but in my area the 10% Trade turns out, after those corrected calculations (thanks ccbill!), to be about a penny cheaper per pound of available chlorine - which essentially means they're just about equal at this moment in time (assuming date codes are recent).

Who knew?
Not me.
Now I do know.
So do you.

 

[setsailsoon]

Gary,

Here's my $.02. Certainly there are lot of folks that benefit from knowing updated locations for best price. So thanks for the update. There's a simple net cost calculator included with Pool Math that makes the calculation very easy to compare different % and price. As to swg, cost for electricity is definitely a part of the operating cost and for me the really huge issue is how much easier pool care becomes... don't forget the cost of travel to and from the store to get the liquid plus the jug lugging aspect. This can be pretty high in your state as well.

Best regards.

Chris

 

[ccbill]

Fwiw, for me the up front cost of an swcg is about the cost of 2-3 years of lc. I get my 10% lc at Home depot. Lately the date codes have been within a week, pretty stoked about that. Pool store 12.5% was cheaper a couple of years ago but not any more. Seems I'm always at the hardware store for something or other so picking up lc is rarely a separate trip - I have a fiften gallon barrel that lasts a while. Every once in a while I have to go to Walmart 'cause HD is out. Walmart lc is usually fresh and cheaper than HD but not worth the xtra driving. If that happened too often I'd be thinking of better options.

 

[red.32]

I too, just get my chlorine from Home Depot. The price is up just a bit from last year, but not too bad. I hardly use anything other than in the summer, so I don't worry a little price difference. Muriatic acid goes way up for some reasons, so I go to Lowe's to get that.

 

[tcat]

I too, just get my chlorine from Home Depot. The price is up just a bit from last year, but not too bad. I hardly use anything other than in the summer, so I don't worry a little price difference. Muriatic acid goes way up for some reasons, so I go to Lowe's to get that.

Weird, here in Texas chlorine went from $8.99 for 3 to $18.99 for 3, and can't be found. MA went from $11.99 for 2 to $16.50 for 2 (not bad). The Chlorine price is the only reason I switched to salt this year.

 

[HermanTX]

Weird, here in Texas chlorine went from $8.99 for 3 to $18.99 for 3, and can't be found. MA went from $11.99 for 2 to $16.50 for 2 (not bad). The Chlorine price is the only reason I switched to salt this year.

You can still buy 1 gal for $5 plus tax at Walmart down in Houston area. Also Pinch a Penny sells 2.5 containers, i.e. 5 gals is $20 plus tax

 

[red.32]

Weird, here in Texas chlorine went from $8.99 for 3 to $18.99 for 3, and can't be found. MA went from $11.99 for 2 to $16.50 for 2 (not bad). The Chlorine price is the only reason I switched to salt this year.

It was about the same $8.99 but for 2 x 128. Now it's about $1 more, but they are always in stock. The power chlorine went way up, at least at Leslie's, and now they keep giving out these 15% off promotions. LOL.

 

[Gyre]

Looks like Home Depot just raised the price to $18 for 2 gallons.

Man, either I need to think about SWCG or hope to find a less jacked-up supplier.