FC/CC readings for bromine spas using chlorine FAS-DPD

wayner · Sep 10, 2014

I have the Taylor K-2006 chlorine test kit. I use the chlorine test in my spa as well- my spa is bromine. I was told I could just multiply by 2.25. So with a 25mL sample each drop indicates an FC of .45.

Is this also true for measuring CC? The CC levels in my spa, assuming the same 2.25 multiplier are generally around 1-2 which is way higher than my pool which is always pretty much 0.

What are the recommended levels for FC and CC for a bromine spa kept at 100F?

JamesW · Sep 10, 2014

Theoretically, bromine should not need to be measured for combined bromine. It should not usually register any CB. However, I have found that it almost always does; although I don't know why.

I would suggest a bromine level of about 4 to 6 ppm. CC or CB should be not more than 0.5.

The reason that you should only need to test for free bromine is that bromine combined with ammonia should register on the free chlorine test. However, there might be other brominated compounds that might not register on the fc test.

There might also be other oxidizing agents in the water such as dissolved oxygen, ozone, monopersulfate, bromate etc.

wayner · Sep 12, 2014

I don't actually have a test for CB since I am using a chlorine test kit or can you convert a CC reading to CB? Is it the same 2.25 mulitplier?

JamesW · Sep 12, 2014

Yes, you do the CC test and multiply by 2.25.

Do you have an ozonator or do you use MPS?

wayner · Sep 15, 2014

No to ozonator and it appears that the sanitizer that I use is MPS although it is only labeled as chlorine free.

JamesW · Sep 15, 2014

Mps will register as CC unless you use the neutralizer to remove the interference.

wayner · Sep 15, 2014

What neutralizer do you mean and where do I get it?

chem geek · Sep 16, 2014

The Taylor K-2042 MPS interference remover.

JamesW · Sep 16, 2014

The mps is probably the cause of the CC/CB. However, I have seen bromine tubs that don't use ozone or mps that still get some reaction on the CC/CB test. Bromamines should react with the first part of the test, so I'm not sure what would be causing the reaction on the second part of the test. I test just to see if there is any reaction but without knowing what is causing the reaction, it's hard to know what to do about it other than just following good practices and maintaining adequate bromine levels.