Poolmath and Bromine

[Biggen]

I know the PoolMath calculator on the TFP website doesn’t calculate bromine levels via adding dichlor as the oxidizer. But can’t I simply divide the amount I want to raise the Br by 2.25 to determine the amount of dichlor I need to add to the spa?

For example, if I want to raise my bromine level from 3 to 10 in a 350 tub, don’t I just divide 7 (the amount of Br I want to raise) by 2.25? 7 / 2.25 = ~3. According to the Poolmath calculator, raising FC by 3ppm requires me to add .3oz of dichlor for a 350g tub. 3 x 2.25 = a 6.75 or a ~7Br input over whatever level of Br that exists in the spa already.

Am I doing this conversion right?

 

[Mdragger88]

I’m having a hard time following your math but for simplicity’s sake:
You would use 1/2 the ppm of chlorine as you wish to increase total Br as Br is roughly 2x’s as heavy as fc
Example:
*If you want 4ppm of total br increase you would use 2ppm worth of dichlor/bleach
* if you want 6ppm of total br increase you would use 3ppm of dichlor/bleach
& so on. If that makes sense.
You can use the 2.25x’s for calculating but 2x’s is close enough generally

 

[Biggen]

I’m having a hard time following your math but for simplicity’s sake:
You would use 1/2 the ppm of chlorine as you wish to increase total Br as Br is roughly 2x’s as heavy as fc
Example:
*If you want 4ppm of total br increase you would use 2ppm worth of dichlor/bleach
* if you want 6ppm of total br increase you would use 3ppm of dichlor/bleach
& so on. If that makes sense.
You can use the 2.25x’s for calculating but 2x’s is close enough generally

Yup. I think we are saying the same thing. Haha! Whatever the increase in Br I want, I divide it by 2 (or 2.25 if you want to be exact) to get the dose of FC equivalent.

Converted my 350g spa over to a 3-step bromine tub so I’ve been working on getting a system down for startup and then continuing balancing everything after that. Keeping pretty meticulous notes so far in a spreadsheet so I’ll remember what I did right and wrong for the next refill in 3 months.

 

[Mdragger88]

PoolMath logs are your friend if you want good records. The summary function is phenomenal for this as well allowing you to see what you added during any specific date range.
For your sodium bromide additions you can just add a note which will show in your logs since its not a listed chemical.