Really High Bromine Per K2106 Test K

[Vince22]

Hi,

I just recently got a Taylor K2106 test kit. I've had no issues with PH, TA, and hardness, but the Bromine test has me scratching my head.

A test with a test strip indicates that my bromine level is at about 1.0ppm. The Taylor FAS-DPD bromine test is indicating over 10ppm!!

I'm pretty sure I'm following the instructions which are to fill the test tube to 44ml, add 5 drops of the first liquid to see if bromine is present (turns pink) and then add the second liquid drop by drop until the color changes from pink to clear/blue. Apparently, each drop = 0.5ppm and I'm getting to over 20 drops before the sample holds a consistent change from the pink.

Is my understanding of this test correct?

Thanks for your help.

[DonR6702]

Hi,

I just recently got a Taylor K2106 test kit. I've had no issues with PH, TA, and hardness, but the Bromine test has me scratching my head.

A test with a test strip indicates that my bromine level is at about 1.0ppm. The Taylor FAS-DPD bromine test is indicating over 10ppm!!

I'm pretty sure I'm following the instructions which are to fill the test tube to 44ml, add 5 drops of the first liquid to see if bromine is present (turns pink) and then add the second liquid drop by drop until the color changes from pink to clear/blue. Apparently, each drop = 0.5ppm and I'm getting to over 20 drops before the sample holds a consistent change from the pink.

Is my understanding of this test correct?

Thanks for your help.

Are you using MPS (non-chlorine) shock to activate your bromine?

I had this problem with the K-2006 Chlorine FAS-DPD test. The conclusion reached by Taylor tech support was that the interference came from MPS (non-chlorine shock). It is well known in the analytical chemistry world that MPS reacts with ferrous ammonium sulfate (FAS, the titrant in the Taylor K-2006 and K-2106 kits), so if you perform the test while there is still significant active MPS in the spa the results will be high, whether you are analyzing free chlorine or bromine. The conventional wisdom is that if you wait "a few hours" after adding MPS, the interference will be gone, as the active component of MPS decomposes and no longer reacts with FAS. But the question is "How many hours are a few?". The answer is, it depends on the overall water chemistry, the water's oxygen demand, and the level of MPS added. Twelve hours after last adding MPS to my spa, I saw interference causing the free chlorine to read about 9.5 ppm too high. The interference diminished slowly over the course of a few days, but it was still present to the extent of about 1 ppm (high chlorine reading) after 10 days. It's still unclear to me why this interference persisted for so long - the Taylor tech support rep was reluctant to blame the reagents in my kit, and I concurred with that since I analyzed chlorine standards made with bleach and bottled water and those analyses worked fine. I can say that my spa water was about 3-1/2 months old and the spa had been used relatively heavily (for my situation at least, perhaps lightly for some of you), so I was preparing to change the water anyway.

I understand that with bromine sanitation you may be adding MPS frequently to activate the bromine. In this case, I think it's important to determine just how much is needed to do the job and avoid adding large excesses. In my case, my spa began leaking around a fitting just before I was going to change the water, so it's now empty and awaiting a service rep. When I fill it again, I will either stop using MPS or at least use it much more sparingly.

Don

[apradman]

I'm also using bromine and non chlorine shock, I normally add a capful with 2 people using the tub for 20 min. Is this correct. I have never read what is the correct amount to add after use.

[DonR6702]

I'm also using bromine and non chlorine shock, I normally add a capful with 2 people using the tub for 20 min. Is this correct. I have never read what is the correct amount to add after use.

I don't use bromine, but I will try to answer.

If you're adding bromide salts once a month or so to maintain a bromide bank, the MPS you add will be used up converting the bromide to bromine, as long as there is sufficient bromide reserve. So in that case it's important to maintain that bromide reserve. Unfortunately there's not a test kit available for bromide, so you have to follow the manufacturer's recommendations for how often to add bromide and how much to add. If you start seeing the bromine level fail to rise after adding MPS, your bromide level is probably low or depleted entirely.

If you're using bromine tablets and just adding the MPS as a shock, try to keep the bromine dispenser full so (hopefully) the bromine level never drops below about 3 ppm, and only add MPS when indicated by water quality issues, when the bromine level can't keep up with the load, or when your experience tells you there's about to be a problem due to usage. I got into trouble by getting into a routine of adding MPS on a regular schedule when it wasn't really needed.

Anyone else out there who uses bromine and MPS, feel free to correct or add to this.

Don

[schmoe]

Vince, I think you might be doing the test wrong. One drop = 0.5 ppm if you are filling the comparator tube to the 25 mL mark, not 44 mL as you said in your post.

[Jim C.]

Vince, I think you might be doing the test wrong. One drop = 0.5 ppm if you are filling the comparator tube to the 25 mL mark, not 44 mL as you said in your post.

I agree. The 44 ml level in the tube is for the pH test. Use the 25 ml or 10 ml marks for other tests. Using 44 ml is going to report a Bromine level almost 2X actual (44/25=1.76).

Bromine levels can get kind of high if you generate a lot of it (by any means -- ozone, chlorine, non-chlorine, etc.) and there is not much organic load to "clean up" to use it up. Just back off on your bromine generation step to get lower levels (but first do the test right to get actual number).

Jim C.