Plan for converting hot tub to bromine

jcushman

Member
Oct 17, 2017
5
Driftwood, TX
Hi,

I currently sanitize my spa with the dichlor/bleach method, but want to change to bromine. I read the long thread about using bromine, but didn't really see this question addressed. I have a 275 gallon portable spa with ozone (one of the reasons I want to change to bromine). I understand that after establishing the bromine bank you need an oxidizer to activate the bromine. Would using the granulated bromine/dichlor after each soak as needed be an effective way of activating the bromine and keeping the bromine bank from depleting?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,855
Tucson, AZ
The bromide bank does not deplete and you typically establish it using sodium bromide. When you add any source of chlorine to the water, the chlorine "activates" (oxidizes) the bromide (Br-) to bromine (Br+). When the bromine sanitizes or oxidizes something, it gets reduced back to bromide again.

The cheapest thing to activate bromide would be plain laundry bleach. You can also use dichlor powder as well. Bromine "tabs" are typically a mixture of brominated and chlorinated dimethylhydantoin (DMH) and so the chlorine is already present to "activate" the bromine. However, just like CYA can over stabilize a chlorine sanitized pool, DMH can over stabilize a bromine pool and make the bromine less and less effective. There is no method for measuring DMH levels like there is for CYA so you just have to be careful with using brominated spa tablets.

I would not count too much on the ozone system helping you out. The ozonators installed on hot tubs are often very cheaply made units that die very quickly (within a year) and there's no way to know if they are or are not producing ozone. Ozone, in theory, should also activate bromine but the units on hot tubs are so under-powered that you really can't tell if they are working or not.
 

jcushman

Member
Oct 17, 2017
5
Driftwood, TX
Thanks for the reply. I have some dichlor granules from when I was using that as my sanitizer. So now I am using that as an activator for the bromine. I understand that I can also use bleach, or non chlorine shock or the bromine granules( which are actually bromide plus dichor). Does the granulated bromine also contain the DMH like the bromine tabs?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,855
Tucson, AZ
You’d have to look up the product info on the granules to know for sure. It could be a mixture of dichlor and sodium bromide or the bromine might be in the form of a DMH compound. The packaging should say. You want to be careful with solid brominated compounds as they typically add DMH and they are quite acidic and will reduce TA over time.
 

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