Why is my Bromine zero?

McAlsop

Member
Jul 30, 2016
10
Mounds View, MN
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

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,876
SW Indiana
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

TFP Expert
Mar 2, 2011
21,553
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

Member
Jul 30, 2016
10
Mounds View, MN
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 :laughblue:]
 

McAlsop

Member
Jul 30, 2016
10
Mounds View, MN
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!
 
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