HTH Pool Shock Numbers not adding up

So I've been reading a bunch of forum posts on using pool shock to keep a sterile rez but the number's I've been seeing do not add up with the pool strip testing that I just finished and the calculations I did after. The number's that I saw was to use 1 gram of 50% calcium hypochlorite powder in 1 gallon of water as your concentrate and 5 ml's per gallon of that concentrate in your reservoir. I just received my pool test strips today and I was testing my res water and it was showing 0 free chlorine at that level. The concentrate itself was showing over 10 ppm's of free chlorine so I knew the test strips were working. Then I went back and calculated what I would actually need and I came up with a number 30x of 1 g/gallon for the concentrate and I'll show my work below. This is the product I'm using which shows to use 13.3 oz per 10,000 gallons to raise ppm's 1-4 of free chlorine.
13.3oz x 28.35 grams/oz = 377.055 grams (converting oz to grams)
377.055 grams/10000 gal = .04 grams/gal This number is what you want unconcentrated to raise your free chlorine ppm's 1-4.
The number most people give is 1g/gallon of powdered ~50% calcium hypochlorite and 5 ml's per gallon of concentrate in your res.
Now 1g/gallon is 25x .04
So in actuality that 1g/gallon is giving you 25 doses or enough to treat 25 gallons of water to raise ppm's of free chlorine 1-4.
3785 ml/25 = 151 ml
151 ml's per gallon of concentrate would raise your free chlorine ppm's by 1-4, not 5ml... confirmed by test strips.
What I propose is to raise the concentrate by 30x, so 30 grams of powdered ~50% calcium hypochlorite per gallon.
30/.04 = 750, so 750 doses per gallon of concentrate.
3785 ml/750 = 5 ml so each dose is now 5 ml and this would raise ppm's by 1-4

TLDR: What I've read people calculate does not raise ppm's of free chlorine and if 1-5 ppm's of free chlorine is safe for cannabis (which I've also read) then the actual dose of pool shock that is suggested is 30x too low. Using 30g of powdered calcium hypochlorite per gallon of water makes a concentrate of which you can use 5 ml's per gallon in your res to raise free chlorine ppm's 1-4.

I'm gonna test this on my aeroponic cloner before I use this on my dwc grow since it does seem fairly radical and even the old 1 g/gallon concentrate with 5 ml/gal res use smells fairly strong. Would love if someone could check my logic/math and add whatever they want. I'm not gonna even bring up chlorine's mixing with nutrients or whatever yet because I just wanna see if my calculation is right.

I use 65% super shock and add .26 grams to a 30 gallon reservoir

Concentrated pool shock doesnt store very well in my experience, even in light proof jugs. Unless you go through gallon jugs of it fairly quickly, there might be hardly any chlorine left by the time you near the end of the jug.

Still I'd like people to comment on my numbers. I'm pretty sure I'm right and the previous threads were wrong. I could use less than 5ml of concentrate but the concentrate being 30x as strong as previously suggested seems right. If you're right about the storage of concentrate not storing well maybe I'll go with .04 or less per gallon of the powder mixed into each gallon but the fact that it does dissipate every few days means I need some kind of concentrate to add to the res. Maybe keeping smaller amounts of concentrate would work out well for storage concerns but I just want to confirm my #'s. Also my previous concentrate of 1g/gallon of powder seems to still be over 10 ppm's of free chlorine 2 weeks later.

It took me a few reads to understand how you got there. There's an easier way to go about this. To me, anyways. It's been a minute since I've even thought about it because I switched to Southern Ag GFF. By my math you were close but, I'm not expert on the matter.

1ppm = 1mg/l
1gal = 3.7854l
I'm going to assume 1g of your pool shock gives .5g or 500mg of free cl. This is because the actual free cl will be slightly less than the percentage of Calcium Hypochlorite.

The 1g/gal mix:
500mg/3.7854l = 132.08mg/l
making that concentrate 132ppm

132.08mg/l = .132mg/ml
You're using 5ml of said concentrate

5ml x .132mg/ml = .66mg
This dose is added to 1gal

.66mg/3.7854l = .174mg/l
So, .174ppm in your final solution.

If you were to use 151ml instead of 5ml,
.174ppm x (151/5) = 5.25ppm

If you were to use 100ml instead of 5ml,
.174ppm x (100/5) = 3.48ppm (This would probably my initial solution since the gal is already mixed and in my experience has a poor shelf life.)


The 13.3oz/10,000gal mix:
That bag says 13.3oz/10,000gal
13.3oz = 377.055g or 377,055mg

Assuming 50% again, we're at 188,527.5mg
188,527.5mg/37,854l = 4.98mg/l

So the 13.3oz bag gives your 10,000gal pool 5ppm

30x dosage:
If you do 30x the 1g/gal dosage
30 x .174ppm = 5.22ppm in your final solution

Now, the easier way to hit a target ppm:
You want a gal of concentrate that will give you 5ppm in your final solution added at 5ml/gal and you have 50% cl.
X = required free cl
Z = required pool shock

Xmg/3.7854l = 5ppm
Xmg = 5mg/l x 3.7854l
18.927mg is the amount of free cl required to bring 1 gal of water to 5ppm.

18.927mg = Z(50%)
Z = 18.927mg / .5
You'll need 37.852mg of pool shock per gallon of solution.

3785.4ml/gal, 5 ml dosage
3785.4ml/ 5ml = 757 doses/gal
757 x 37.852mg = 28,653.964mg

28.66g of pool shock per gallon of concentrate.

You can reuse those last couple equations with different a target ppm or free cl%.

Hope this helps and I didn't fuck it up. Without a for sure %free cl, there's always going to be a built-in assumption, unfortunately.

I appreciate you going over the numbers and including more calculations, will definitely use that to try and approximate 2-3 ppm's of free cl. I can also use my test strips to show approximately how much free cl there is as well but it's not extremely accurate between 1 and 5. All I know is that the 1g/gal concentrate was not strong enough according to my calculations and your calculations confirm that. No idea how they arrived at that conclusion.

GreenhouseGreen said:

It took me a few reads to understand how you got there. There's an easier way to go about this. To me, anyways. It's been a minute since I've even thought about it because I switched to Southern Ag GFF. By my math you were close but, I'm not expert on the matter.

1ppm = 1mg/l
1gal = 3.7854l
I'm going to assume 1g of your pool shock gives .5g or 500mg of free cl. This is because the actual free cl will be slightly less than the percentage of Calcium Hypochlorite.

The 1g/gal mix:
500mg/3.7854l = 132.08mg/l
making that concentrate 132ppm

132.08mg/l = .132mg/ml
You're using 5ml of said concentrate

5ml x .132mg/ml = .66mg
This dose is added to 1gal

.66mg/3.7854l = .174mg/l
So, .174ppm in your final solution.

If you were to use 151ml instead of 5ml,
.174ppm x (151/5) = 5.25ppm

If you were to use 100ml instead of 5ml,
.174ppm x (100/5) = 3.48ppm (This would probably my initial solution since the gal is already mixed and in my experience has a poor shelf life.)


The 13.3oz/10,000gal mix:
That bag says 13.3oz/10,000gal
13.3oz = 377.055g or 377,055mg

Assuming 50% again, we're at 188,527.5mg
188,527.5mg/37,854l = 4.98mg/l

So the 13.3oz bag gives your 10,000gal pool 5ppm

30x dosage:
If you do 30x the 1g/gal dosage
30 x .174ppm = 5.22ppm in your final solution

Now, the easier way to hit a target ppm:
You want a gal of concentrate that will give you 5ppm in your final solution added at 5ml/gal and you have 50% cl.
X = required free cl
Z = required pool shock

Xmg/3.7854l = 5ppm
Xmg = 5mg/l x 3.7854l
18.927mg is the amount of free cl required to bring 1 gal of water to 5ppm.

18.927mg = Z(50%)
Z = 18.927mg / .5
You'll need 37.852mg of pool shock per gallon of solution.

3785.4ml/gal, 5 ml dosage
3785.4ml/ 5ml = 757 doses/gal
757 x 37.852mg = 28,653.964mg

28.66g of pool shock per gallon of concentrate.

You can reuse those last couple equations with different a target ppm or free cl%.

Hope this helps and I didn't fuck it up. Without a for sure %free cl, there's always going to be a built-in assumption, unfortunately.

Click to expand...

I literally just bought a bag of pool shock for a 27gal rez. I saw the directions of how much to use per 10,000gal and said fuck this math. So thank you! You saved me a good 15 minutes of trying to math.

I use a pool shock solution for my aero cloners, but I use Dutch Master Zone in my flowering reservoirs. I should say 'used', because DM went out of business and I just ran out of the Zone. The active ingredient is copper sulfate, so I'm going to try to make my own version to see if I can match the effects. It works amazingly well, and I only have to add it with each rez change and I'm done until the next. I don't want to keep adding calcium hypochlorite to my flowering rezes like I do to my cloners. Will see how it goes...

tyler.durden said:

Dutch Master Zone

Click to expand...

i used this too many years ago.

i read that Fuji Industries bought dutchmaster and they were going to start making Zone again but i haven't seen it available anywhere

wonder if this would work?

rkymtnman said:

i used this too many years ago.

i read that Fuji Industries bought dutchmaster and they were going to start making Zone again but i haven't seen it available anywhere

wonder if this would work?

Copper Sulfate Granular Crystals - Southern Agricultural Insecticides, Inc.

Controls smelly, ugly algae in ponds & lakes

southernag.com

Click to expand...

Yep, that's the stuff. They have other brands on amazon that may be cheaper. I can't find much literature on using it for hydroponics, but I did find some on aquarium sites. They talk about controlling algae in their tanks at a level that won't burn their fish. It seems you have to mix the CS crystals with equal parts citric acid to make the copper solution stable. I'm going to start with that fish level to see the effectiveness, and go up or down from there for my plants. I hate having plenty of money to spend on a product (zone) that is not available, seems unnatural

My brain can't comprehend this. I have 56% Pool Shock. I want to use it in my 30 gallon res. I'm cool with making up a gallon of concentrate or adding it directly into the res. What are the numbers I need to accomplish this?

lusidghost said:

My brain can't comprehend this. I have 56% Pool Shock. I want to use it in my 30 gallon res. I'm cool with making up a gallon of concentrate or adding it directly into the res. What are the numbers I need to accomplish this?

Click to expand...

0.30 grams is 1ppm chlorine for you

rkymtnman said:

0.30 grams is 1ppm chlorine for you

Click to expand...

So weigh out .30 of crystals, throw them in the res, and boom, good to go?

Thanks, man!

lusidghost said:

So weigh out .30 of crystals, throw them in the res, and boom, good to go?

Click to expand...

bada bing, bada boom. easy enough huh?

you can go up to 5ppm

Is there a way to add calcium hypochlorite to hydrobuddy using "add a substance"? And then I could just change the "Cl" number if using a different pool shock product (meaning a product that might have a different "calcium hypochlorite" percentage (on the bag)). I've 40ish%, 50%, 52%, 60%, 65%, and 70% products.

I found some online calculators. They don't explain or outline the math/steps though. I'll try and compare against @GreenhouseGreen 's math above (thanks for that, by the way. I'll try and figure it out.)

@GreenhouseGreen Can I ask you about the math regarding this? And do your calculations align with this online calculator: https://www.handymath.com/cgi-bin/chlorined.cgi?submit=Back+to+Calculator&numnum=1&initvol1=1&initconc1=0&fnlconc1=50&wghtpercnt1=70&iv2=selected&sw3=selected
Thanks.