Crazy Reaction when Testing for Bromine in Hot Tub

[KSpoolguy]

So, I've been following the BBB method for years. We built our pool in 2013 and switched over that same summer after finding this site (and after having multiple problems with multiple pool store runs). Of note, we have an older Jacuzzi hot tub at our lake house. The first summer we owned the lake house, we went with bromine for chlorination, as we could put a floater in there and it would be sparkling clean a week or so later when we came back. In 207, we started renting out our lake house on VRBO and there were no hot tub companies close enough to service it. So we just keep it empty and fill it up when we are there and then drain it before we leave (and we strictly use bleach/liquid chlorine for sanitation).

This spring we bought a Sundance 780 Chelsee spa for our main house. I was strictly using bleach for chlorination (after the spa guy started it up using MPS and some other chlorine powder - I did follow that for a week but didn't have great results and switched over to just straight bleach with great results). However, we went out of town for quite a few days a few weeks back and decided to switch over to bromine (like I had done before with our hot tub at our Lake house). We followed the recommended bromine startup procedures found on this site (same I used before at the lake house spa).

Anyway, two nights in a row I have tested the bromine using the TF-100 and the strangest thing has happened both times. I searched this site for similar situations and could not find another thread on it.

Here goes: I added the spa water in the testing tube to 10 ml. I added the R-0870 powder and the solution turned a slight pink. I then added R-0871 one drop at time. After 2 drops, it turned clear. However, this is where the strange thing happened. Within a few seconds, without adding anything else, it started to slowly turn pink again. There was no undissolved R-0870 powder in the solution. And I just did the test again and same thing happened.

Has this happened to anyone else? I have never seen this in the almost 10 years of testing pool and spa water. Is it related to using bromine? I'll admit, my experience with bromine is limited to that one summer we kept the lake house hot tub filled and we had great results with it. However, I am now stumped.

And does anyone have a better idea than bromine with understanding that we travel quite a bit to our lake house through the year, sometimes for a week at a time?

 

[ajw22]

The FAS/DPD test is over when the sample turns clear. If you let the sample sit a while it will turn pink again. That means nothing.

Do you have ozone or UV in your spa?

I will let @RDspaguy or others work with you on the best way to main tin your spa water.

 

[KSpoolguy]

Yep, it has both UV and ozone. I just had never heard or read on turning pink again on that test when using bromine. I searched and searched. Thanks for clearing that up!! So no way to check for CC's or bromines version of it?

Thanks for the insight!!! Much appreciated!!

 

[ajw22]

Testing for bromine and chlorine are the same. The tests are for halogen where bromine and chlorine will both react whether it is an OTO, DPD or FAS-DPD test. The only difference is that technically bromine is 2.25 times heavier than chlorine which is why the test kits have dual scales with bromine twice as high as chlorine.

Wait, what? Combined bromines aren’t measured like CC?

I’m the caretaker for 2 spas in NYC. ~1200 gallons each Use bromine tabs/liquid chlorine CH 225 pH 7.2-7.5, creeps up to 7.8, lowered with liquid muriatic acid 95* F I’ve been chugging along for 15 months with my tf-100 (with refreshed reagents). Somehow I missed that combined bromines aren’t...

www.troublefreepool.com

 

[KSpoolguy]

That's how I thought it was. But it's hard to test for CC's when the test starts turning pink again before you have a chance to add the 5 drops of R-0003. It's almost instant that it changes back to pick after it turns clear when adding R-0871.

 

[ajw22]

If you have bromine there is no reason to test for CCs.

 

[KSpoolguy]

Thanks! That clears it up!

 

[RDspaguy]

Does your Sundance have the 24/7 circulation pump?
I'd recommend you use chlorine, and shock before you leave and again when you get back. If you like, toss a barely open floater in. This will be damaging to equipment and cover over time, but for occassional use is fine.