Tried a bromide salt spa with SmarterSpa...help!!!

[Mdragger88]

I guess the confusing part is that if I have say 1500ppm of Sodium Chloride, having only 30ppm of sodium bromide in the tub means that my SWG will now make bromine?

No, Your swg will make chlorine which will then be converted to bromine because of the sodium bromide bank present in the water.
Your swg only directly creates bromine at the higher sodium bromide levels listed in the manual.
At least that is what I gather from the manual & the operation of other generators that are capable of doing both things.

The tub will be bromine instead of chlorine even though NaCl is 1500ppm and NaBr is only 30ppm?

Yes- Once sodium bromide is in the water any chlorine added then turns into bromine -
You can turn a chlorine tub/pool into a bromine tub/pool but you cannot convert the other way around without replacing all the water to remove the sodium bromide as it generally never goes away.
There’s even a saying, “Once a bromine pool always a bromine pool”.

 

[Mdragger88]

I have to ask, is there a specific reason you chose bromine?
In my opinion it just adds extra complexity & expense when you already have one of the best swg’s around capable of giving you a wonderful chlorine tub experience.

 

[JoyfulNoise]

Since you rang me up, let me interject.

In a mixed salt solution, an SWG can create both chlorine gas and dibromine at the same time. In fact, the oxidation potential is nearly 0.3V lower than chlorine so the cell will preferentially create more bromine than chlorine. However, the chlorine created will also oxidize the bromide to bromine, so the tub will only have bromine in it.

Bromine will mostly form hypobromous acid (HOBr) at typical tub water pH but, because the water is slightly alkaline, there will be a small amount of hypobromite (OBr-) in equilibrium. The amount of hypobromite will be very high right near the cell plate because the pH is a lot higher inside the cell and this will result in the disproportionation of hypobromite in bromide ions and bromate. Bromates are not very good for your health as they are carcinogens (but not readily absorbed through the skin, you’d need to ingest tub water to be exposed). So, all that chemical Mumbo-jumbo is to say … it’s really not a good idea to use an SWG to generate bromine.

Either go full chlorine only OR use standard bromine chemicals. I wouldn’t mix and match.

 

[Methuselah]

Since you rang me up, let me interject.

Either go full chlorine only OR use standard bromine chemicals. I wouldn’t mix and match.

Thanks for chiming in, great read - I always look forward to your postings

 

[Mdragger88]

Since you rang me up, let me interject.

In a mixed salt solution, an SWG can create both chlorine gas and dibromine at the same time. In fact, the oxidation potential is nearly 0.3V lower than chlorine so the cell will preferentially create more bromine than chlorine. However, the chlorine created will also oxidize the bromide to bromine, so the tub will only have bromine in it.

Bromine will mostly form hypobromous acid (HOBr) at typical tub water pH but, because the water is slightly alkaline, there will be a small amount of hypobromite (OBr-) in equilibrium. The amount of hypobromite will be very high right near the cell plate because the pH is a lot higher inside the cell and this will result in the disproportionation of hypobromite in bromide ions and bromate. Bromates are not very good for your health as they are carcinogens (but not readily absorbed through the skin, you’d need to ingest tub water to be exposed). So, all that chemical Mumbo-jumbo is to say … it’s really not a good idea to use an SWG to generate bromine.

Either go full chlorine only OR use standard bromine chemicals. I wouldn’t mix and match.

I thought maybe you were napping or away- & I knew you’d have all the sciencey deets!
Now that you’re on the horn… I’m seeing conflicting information- is the higher sodium bromide level necessary for the cell to directly produce bromine? The manual makes it seem like this is the case & there is mention of this in regards to other units like here

Using Chlorine generator with Bromine

Is it possible to use a Chlorine generator and saltwater as the oxider to activate the sodium bromide? I am using the 3 step process now with the bromide tablets and MPS for weekly shock. Could I use saltwater and the Chlorine generator instead of the bromide tablets? Thanks!

www.troublefreepool.com

That method seems like an expensive endeavor especially when spas should be drained & refilled regularly.

 

[JoyfulNoise]

I thought maybe you were napping or away- & I knew you’d have all the sciencey deets!
Now that you’re on the horn… I’m seeing conflicting information- is the higher sodium bromide level necessary for the cell to directly produce bromine? The manual makes it seem like this is the case & there is mention of this in regards to other units like here

Using Chlorine generator with Bromine

Is it possible to use a Chlorine generator and saltwater as the oxider to activate the sodium bromide? I am using the 3 step process now with the bromide tablets and MPS for weekly shock. Could I use saltwater and the Chlorine generator instead of the bromide tablets? Thanks!

www.troublefreepool.com

That method seems like an expensive endeavor especially when spas should be drained & refilled regularly.

You need the water in the cell to have a specific conductivity in order for the cell to operate efficiently. The only way to do that is by using a salt to increase the conductivity of the water. The particular details of which salt to use doesn't matter in terms of the electrical performance BUT it obviously makes a difference if you factor in things like cost and availability. Sodium chloride is cheap, $6 for a 40lbs bag. Sodium bromide “salt” is A LOT MORE expensive than that. So filling a tub with enough NaBr to get the conductivity in the right range is a HUGE waste of money. It’s better to set the conductivity to the correct range using regular sodium chloride and then add enough NaBr to create a 30-50ppm bromide bank. In that scenario, the NaCl is only creating the correct conductivity and not participating in creating a sanitizing halogen.