# Thread: Pool Math has FC, but I'm using Bromine. Converting with 2.25

1. ## Pool Math has FC, but I'm using Bromine. Converting with 2.25

I can never seem to find this conversion number so I'm putting it here.

Taylor K-2106 tests for Total Bromine. Pool Math doesn't have a Bromine area. It has Free Chlorine (FC). The conversion is with 2.25.

I use the K-2106 kit and test for Total Bromine (Br-), pH, Total Alkalinity (TA), Calcium Hardness (CH).

Then, I head down to the bottom of Pool Math to the "Suggested Goal Levels" area and select "Traditional Spa".

I make sure I have the correct gallons and temperature entered.

I'm using Borates, so I enter 50 in both Now and Target since I set it and forget it.

I type in my pH, TA, and CH "Now" measurements, noting that there is no Total Bromine area. Pool Math has Free Chlorine (FC).

After selecting Traditional Spa, the FC area will show "Goal: 1 to 6" This gets a little confusing, because those numbers are good goals for a spa, either Bromine or Free Chlorine, but those numbers don't affect the automatic calculator portion of Pool Math. They're just telling you that if you you're on Chlorine, aim for those numbers. However, you will mess up your Bromine settings in your spa if you ignored the fact that the numbers that you have to enter into Pool Math must be FC, not Total Bromine that your K-2106 test kit will show you after doing a Total Bromine Test. You have to convert your Total Bromine findings by dividing Total Bromine by 2.25.

Example:

I test with Taylor K-2106 and my spa's Total Bromine result is 0.5 ppm. But, what I really want is 2.0 ppm Total Bromine. Since Pool Math only has FC area, I have to convert with 2.25 so I can tell it FC.

0.5 / 2.25 = .222 (I enter .222 into Pool Math, FC, "Now" box)

2.0 / 2.25 = .889 (I enter .889 into Pool Math, FC, "Target" box)

Then, since the Bleach that I am using is 8.25% concentration, I type "8.25" in the box next to "weight" % bleach.Jug size..."

The result I am looking for is the "Add ?.? oz" (to the left of my bleach percentage). This number automatically gets calculated and will change based on the Now, Target, and % bleach number you provide.

In my example, with a Now of .222 and Target of .889 and 8.25% bleach, it shows "Add 0.4 oz of 8.25 weight % bleach. Jug size ??? (jug size doesn't matter)"

If I mouse over the "Add 0.4 oz", I will see "2 tsp" pop up in the "Mouse over a field for detail" white box at the top. This lets you know that 0.4 oz is the same as 2 teaspoons.

I then go add 2 teaspoons of 8.25% bleach to my hottub to raise the Total Bromine level from 0.5 ppm to 2.0 ppm.

Attachment 45223

2. ## Re: Pool Math has FC, but I'm using Bromine. Converting with 2.25

I've seen the conversion buried in some other posts like HERE, but can be difficult to find at times. Some threads get very lengthy. Your illustration reads well and I came-up with the same numbers.

3. ## Re: Pool Math has FC, but I'm using Bromine. Converting with 2.25

Originally Posted by heykerrdog
You have to convert your Total Bromine findings by dividing Total Bromine by 2.25.

Example:

I test with Taylor K-2106 and my spa's Total Bromine result is 0.5 ppm. But, what I really want is 2.0 ppm Total Bromine. Since Pool Math only has FC area, I have to convert with 2.25 so I can tell it FC.

0.5 / 2.25 = .222 (I enter .222 into Pool Math, FC, "Now" box)

2.0 / 2.25 = .889 (I enter .889 into Pool Math, FC, "Target" box)

Then, since the Bleach that I am using is 8.25% concentration, I type "8.25" in the box next to "weight" % bleach.Jug size..."

The result I am looking for is the "Add ?.? oz" (to the left of my bleach percentage). This number automatically gets calculated and will change based on the Now, Target, and % bleach number you provide.

In my example, with a Now of .222 and Target of .889 and 8.25% bleach, it shows "Add 0.4 oz of 8.25 weight % bleach. Jug size ??? (jug size doesn't matter)"

If I mouse over the "Add 0.4 oz", I will see "2 tsp" pop up in the "Mouse over a field for detail" white box at the top. This lets you know that 0.4 oz is the same as 2 teaspoons.

I then go add 2 teaspoons of 8.25% bleach to my hottub to raise the Total Bromine level from 0.5 ppm to 2.0 ppm.

Attachment 45223
A nice simple easy to understand post and I have to come along two years later to say that I think it is wrong.

I have to convert with 2.25 so I can tell it FC.
0.5 / 2.25 = .222 (I enter .222 into Pool Math, FC, "Now" box)

You should have stopped there.
You have your Bromine reading translated to Chlorine levels that PoolMath can understand and it will crank out the numbers to get you to a sanitizer level that you need.
End-of-Story
If you leave the "2" in the Target level it should spit out something around 1.1 Oz not "2 tsp". (You must be running very low sanitizer levels.)

That "2" target would translate to 2 * 2.25 = 4.5 ppm bromine level which is in the 4-6 PPM recommended in the thread
How do I use Bromine in my spa (or pool)

The upper end of that range would be 6 / 2.25 = 2.67 so you could put 2.67 into the target if you wanted to be on the top edge of that range.
Sorry

4. ## Re: Pool Math has FC, but I'm using Bromine. Converting with 2.25

Originally Posted by dsime42
A nice simple easy to understand post and I have to come along two years later to say that I think it is wrong.

I have to convert with 2.25 so I can tell it FC.
0.5 / 2.25 = .222 (I enter .222 into Pool Math, FC, "Now" box)

You should have stopped there.
You have your Bromine reading translated to Chlorine levels that PoolMath can understand and it will crank out the numbers to get you to a sanitizer level that you need.
End-of-Story
If you leave the "2" in the Target level it should spit out something around 1.1 Oz not "2 tsp". (You must be running very low sanitizer levels.)

That "2" target would translate to 2 * 2.25 = 4.5 ppm bromine level which is in the 4-6 PPM recommended in the thread
How do I use Bromine in my spa (or pool)

The upper end of that range would be 6 / 2.25 = 2.67 so you could put 2.67 into the target if you wanted to be on the top edge of that range.
Sorry
I see what you're saying, but no, not correct.

If I simply stopped at the .222 "Now" conversion, I don't have the bromine "Target" that I want. Using a 2 as a Target does not give me the 2.0 Bromine level that I want, it gives a 4.5 Bromine level, because the calculator is specifically set up for FC, which is 2.25 greater than Br-

You're missing my point. I don't want 4.5 ppm Bromine. Too stinky. Too hard on my skin.

I want a Total Bromine Target of 2.0 (which, yes, is lower than recommended in the thread, but what I prefer)

Again, since the calculator doesn't have a place for Total Bromine, which is what my Taylor test kit tests, I have to make my own Total Bromine Target and convert it to a Free Chlorine (FC) Target for the pool math calculator to use. So, my FC Target is .889

Hence, .889 FC Target in order to get the calculator to tell me how much 8.25% bleach I need to add to reach a 2.0 Bromine level.

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