Why is my Bromine zero?

[McAlsop]

So this is the first time I'm trying to use the 3-step method in my 390 gallon hot tub. I have the TF-100 test kit.

Added brand new water, pH/TA was 7.5/220 which is normal; so I added Sodium Hydrogen Sulfate ~14oz and now my pH/TA is 6.8/110.

I am still going to get my pH back to 7.5ish, but I started with the first step which is add Sodium Bromide.

I added 2oz (bottle says "add 1/2 ounce of Sodium Bromide for every 100 gallons of spa water to establish a 30 parts per million bromide reserve")

Now according to my understanding reading the above method, I should use the Orthotolidine test and it should be blindingly yellow as the highest values is 10ppm and I added enough to get it to 30ppm.

The test is completely clear, no bromine at all. What am I misunderstanding? Do I need to add a cup of bleach before testing?

Thanks for reading!

 

[JohnT]

Try diluting your water sample with 3 or 4 parts tap water to be sure you aren’t crazy off-scale. The test turns brown when you get higher with chlorine.

 

[JamesW]

Bromine is not the same thing as bromide.

It's analogous to adding sodium chloride, which adds salt but not chlorine. Chloride can be converted into chlorine by electrolysis in a salt cell.

You added sodium bromide, which is just a salt.

Bromide gets activated into bromine by a oxidizer like chlorine.

So, you can add some sodium hypochlorite to get some bromine.

Note: Don't store the sodium bromide near any Energizer or Duracell products because that would be a salt and battery.

 

[McAlsop]

Thank you! That actually helped a few things finally click for me.

I added 1+3/4 cup of 6% bleach. For the first shock is that a reasonable amount? (The only suggestion in the initial article is about "3/4 cup per 250-300 gallons" - but I read that to be the weekly maintenance dosage and not sure it applies to the initial shock.)

I'll report back with measured levels later today.

[also, I actually looked for batteries around the sodium bromide before I got the joke ]

 

[McAlsop]

That worked exactly as expected. The bromine result (OTO) went to 10ppm+ then dropped back down to ~6ppm within a couple hours. I put my inline bromine cartridge in and will check it daily for the next couple weeks, adding about 3/4 cup 6% bleach each week, or modifying that as necessary.

If any of that sounds wrong, please let me know!

Thanks for your help!