Converting from Bromine to Chlorine

[BobbyR]

Hi all. I want to convert my pool from bromine to chlorine and I've read the threads I can find on conversion but I still don't really understand the issue. I've been running bromine in my pool and spa for about ten years without much trouble. The water in both is clean and sparkling so I'm not battling any water issues but it's just becoming too expensive for the bromine tabs. I run my pool in the mid 80s and, at that temperature, the tabs don't last very long and are costing me hundreds of dollars a season so I want to change over to Chlorine. We are away a lot so the BBB system using liquid Chlorine may not be practical so I'll use a chlorinator with pucks. I understand that the Bromine will remain in the water if I don't drain and refill but I don't see why it matters. What problem is being solved by draining the water to get rid of the bromine? Why can't I just add some CYA and start using Chlorine pucks and shocking with liquid chlorine? In other words, why can't I just start running a Chlorine pool and ignore the Bromine? Will the chlorine/bromine mix not sanitize the water? I'm not a chemist but I can't see how the two would interact in such a way as to make both ineffective. If the bromine persists for a season or two, so what?

As an aside, if bromine really persists in a pool and can be continually re-activated by shocking with liquid chlorine, why is it even required to continually add bromine to a bromine pool? Why not build up the bromine reserve, then just shock with chlorine once a week and stop adding bromine? This may sound silly but it's a logical extension of the idea that bromine persists in the water indefinitely.

Current water test results
Temp 87F
Bromine - 4ppm
pH - 7.6
TA - 120
CH - 270


Thanks for any advice. Looking for the easiest way to accomplish this conversion and to save some money on bromine which has become ridiculously expensive.

 

[JasonLion]

What you can do right away is stop using bromine tabs and start using chlorine to reactivate the bromine. You will still have a bromine pool, but it won't cost nearly as much. The key is that there is bromine in the water, so it will behave like a bromine pool and you should use the bromine target levels and not add CYA.

Eventually someday the bromine level will get low enough so you can start treating it like a chlorine pool, which means different target levels and less total chlorine added. But that will probably be a year to three years from now.

When bromine gets used up it converts to bromide. Adding chlorine converts bromide back into bromine. So it is still a bromine pool even if you are adding chlorine, until all the bromine/bromide goes away. Bromine/bromide breaks down very very slowly, you also lose some to splash out, overflow, backwashing, winterizing etc.

 

[BobbyR]

Thanks for your answer. If I understand this correctly, I can run my pool for a year or so with no bromine pucks and just adding liquid chlorine? That will be a lot less expensive as long as the bromine level stays high enough to sanitize between chlorine additions. This sounds like a plan. I'm going to try this and see if it works.

Just so I know, what would happen if I did add CYA and started running a chlorine pool with chlorine pucks on top of the bromine? I would have a hybrid Br/Cl pool. What would be the problem with that?