Bleach Equivalents to "Shock"

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M

Mithel

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Jul 14, 2013
27
Minnesota
I've owned my pool for fourteen years now and most years it's been fairly simple to maintain the water, but this year was "difficult" so I decided to do some research and stumbled on this site.

My question is: What is the equivalency between liquid bleach and a one pound bag of shock?

I just went to the store and bought several gallons of 8.25% bleach ($4 per gallon) and now I'm wondering how much bleach is equivalent to using a typical bag of shock?

My pool is about 25,000 gallons (oval 18'x36') and usually I can shock (once a week) with two or three bags of shock.
 
I'm not looking for a *precise* answer. Just something rough like 32 ounces of 12% bleach is about equal to a pound of shock (thus at 6% bleach you'd need 64 ounces). But I have no idea if one gallon of bleach is equal to one pound of shock or ten pounds of shock!

Very cool calculator! Thanks!
 
The problem is you would have to know the ingredient in the "shock" to properly compare. If you want to know the equivalent of trichlor to bleach then we can do it. That's why around here the term shock is a process not a product.
 
Yes, post the ingredients of the "shock".

For example (from the poolcalculator.com), 1 lb of dichlor will raise your pool 2.7 ppm FC. It will take 102 ounces of 8.25% bleach to raise it the same amount.
 
Yes, but I'm not looking to "compare". I'm trying to get a "rough feel". So is a gallon of bleach roughly one pound of "shock" or ten pounds (or twenty or whatever)?

Thank you linen, that's exactly what I wanted to know... so roughly 102 ounces of 8.25% bleach is about the same as 1 lb of dichlor. Thanks!
 
Mithel said:
I've owned my pool for fourteen years now and most years it's been fairly simple to maintain the water, but this year was "difficult" so I decided to do some research and stumbled on this site.

My question is: What is the equivalency between liquid bleach and a one pound bag of shock?

I just went to the store and bought several gallons of 8.25% bleach ($4 per gallon) and now I'm wondering how much bleach is equivalent to using a typical bag of shock?

My pool is about 25,000 gallons (oval 18'x36') and usually I can shock (once a week) with two or three bags of shock.
Click to expand...


Welcome to TFP. You say you are having "trouble" this year, so we will be naturally curious to ask you with what? You may likely have very high CYA levels from using the shock and other dry and powdered chlorine products. I encourage you to check out everything you can in Pool School here at the top right of every page. We have a different philosophy than pool stores and most pool service folks as most of us prefer bleach for it's lack of bad side effects. Hope you stick around and see what's here. You'll find some very knowledgeable and experienced people that love helping others. Enjoy the forums!
 
Bleach is 6% or 8.25 %. Liquid "Pool Shock" is 10% or some 12%. The bags of powder also vary in chlorine percentage. That's why it's hard to give you a straight answer. If you read the chemical composition on the bag or if you post a brand name and product name, someone will look it up. But of course the main problem with any chlorine source that comes in any solid form (powders or tablets) is that it adds unwanted chemicals to your pool.
 
The biggest thing you should take away from this "apples to oranges" comparison is that by pitching in 3 or 4 bags of "shock"--------you are most likely still not reaching the actual shock LEVEL of FC required for your level of CYA. You're just temporarily raising that level. (and adding other stuff as well)
 
Mithel said:
Yes, but I'm not looking to "compare". I'm trying to get a "rough feel". So is a gallon of bleach roughly one pound of "shock" or ten pounds (or twenty or whatever)?

Thank you linen, that's exactly what I wanted to know... so roughly 102 ounces of 8.25% bleach is about the same as 1 lb of dichlor. Thanks!
Click to expand...
Assuming it is di-chlor..."shock" could also be cal-hypo, which comes in many different strengths. Or non-chlorine monpersulfate.
 

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Bleach is not always sold in gallons. It used to be sold as 96 ounces (3/4 gallon) or 182 ounces (1.42 gallons) when it was 6%, but now that it is 8.25% it is often sold as 64 ounce (1/2 gallon) and 121 ounce (0.95 gallons).

A "bag of shock" can be virtually any size and its contents may contain nearly pure Dichlor or Trichlor (less common in granular form), or it may contain Cal-Hypo in 48%, 65% or 73% concentration (or similar concentrations) or may contain non-chlorine shock (43% MPS). Also, any of these may be cut down in concentration, cut with other chemicals, etc.

One pound of Dichlor is equivalent to 100 fluid ounces (0.78 gallons) of 8.25% bleach.
One pound of Trichlor is equivalent to 165 fluid ounces (1.29 gallons) of 8.25% bleach.
One pound of 65% Cal-Hypo is equivalent to 117 fluid ounces (0.91 gallons) of 8.25% bleach.
One pound of non-chlorine shock (43% MPS) is "equivalent" to 36 fluid ounces (0.28 gallons) of 8.25% bleach, but non-chlorine shock is not the same as chlorine.

The entire question of equivalency is really a moot point because you should be adding the amount of chlorine that is necessary and that means using a proper test kit (the TFTestkits TF-100 or the Taylor K-2006) to determine how much Free Chlorine (FC) you need for your Cyanuric Acid (CYA) level by following the Chlorine / CYA Chart. Use The Pool Calculator to calculate dosage based on the FC amount that you need for your pool size.
 
I am guessing you are trying to follow some pool stores recommendation about adding a powder once a week or something. That is not what we teach.

If you gave a problem, you need to follow the SLAM process. [slam:1x4mqoso][/slam:1x4mqoso]
 
I'm overwhelmed by how helpful everyone is trying to be. So here are the ingredients of the two forms of shock I've used most for many years:
Aqua Chem:
53.5% Trichloro-s-triazinetrione
Aqua Chem Plus:
58.2% Sodium dichloro-s-triazinetrione

Typically I can use two to four one pound bags to "shock" the pool once a week or maybe twice a week and the pool has been nice and clear.

This year we had a late summer (snow in May!) and a lot of rain. The pool was very cloudy up until last week (after putting literally hundreds of pounds of chemicals into it and several bottles of algeacide). Finally it cleared up, but then we had a burst of rain and now it's cloudy again. The pool store says my chemicals are nearly perfect now. Anyway, I got tired of buying and dumping massive amounts of chemicals into the pool so I found this website.

Although the pool store thinks my chemicals are near perfect, from reading here, I think my CYA is *far* too high. Their test reports read ">100" (and one read ">193"). So from what I'm reading, my chlorine isn't working because of too much CYA (stabilizer).

Anyway, I thought I'd try plain bleach as this site seems to advocate (although from what I'm hearing so far today bleach really isn't any cheaper than bags of "shock"). And yes again, I know I asked an imprecise question and several people did give me an answer which was what I wanted (being very crude one bag of shock equals about one gallon of bleach). Now I'll continue to learn and get more precise.
 
Mithel said:
Anyway, I thought I'd try plain bleach as this site seems to advocate (although from what I'm hearing so far today bleach really isn't any cheaper than bags of "shock").
Click to expand...

cost-comparison-of-chlorine-sources-t1859.html

This explains the cost between sources. I will save you some of the technical reading,

Trichlor Tabs/Pucks ......... $2.20 / 0.915 = $2.40 but $3.83 when accounting for Washing Soda to adjust pH
Dichlor .......................... $2.60 / 0.554 = $4.70 but $5.73 when accounting for Washing Soda to adjust pH
73% Cal-Hypo ................ $2.40 / 0.724 = $3.31
Lithium Hypochlorite ....... $6.00 / 0.352 = $17.05
12.5% Chlorinating Liquid . $0.336 / 0.108 = $3.11
6% Bleach ..................... $0.15 / 0.057 = $2.63
Click to expand...

Plus you already have such high CYA that you will need to do a significant drain and refill, especially if it is actually over 193. Using Trichlor or Dichlor you will have these problems continuously while bleach will not cause them. So be sure to factor that in to the actual cost of using "shock" as well.
 
Donldson, thank you. I appreciate the very nice review of costs. That's what I was starting to think from reading the website that by using bleach instead of dichlor/trichlor that the savings would really be in not needing the other chemicals. (this thread wasn't meant to be a cost comparison, I was just trying to get a rough feel of how much bleach to use compared to how much "shock" I was using)

Thanks again to everyone for the excellent responses.
 
I was originally told by the pool store "experts" to keep a couple pucks in a floater and shock the pool at least once a week or after any high bather use.

Now that I know how to manage the pool, I haven't shocked the pool in eight years. It's just not necessary. If you just keep the water properly balanced it just stays crystal clear and you never have any problems.
 
Since you should be able to get the Fleetfarm LC at $10 for 4 gallons of 12.5% pretty much all the time. You may very well save money since the line in chem geeks table would change:
12.5% Chlorinating Liquid . $[s:31m1p8lz]0.336[/s:31m1p8lz]0.207 / 0.108 = $[s:31m1p8lz]3.11[/s:31m1p8lz]1.91
Click to expand...

On a side note...I would not buy more than you plan to use in a month. The higher percentage LCs loose their potency fairly quickly.
 

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