Switch to Dichlor

[Brewman]

I'm using bromine (Brilliance brand, it it even matters), and I intend to switch to dichlor at my next water change- Maybe in another month to 6 weeks.  Earlier if the weather warms up enough.  

Anyway, I might run out of bromine before that, maybe a couple weeks prior to the water change.  I don't want to buy more Brilliance- the smallest quantity costs almost $20 and would last for several months.  

Is is feasable for me to just let the bromine readings go to zero, then start using dichlor?  I've heard the saying "Once a bromine tub, always a bromine tub".
It's accepted that the way to switch is to change the water and start over.  

What would happen if I just started dosing with dichlor for a couple weeks?  Would I be able to accurately test  chlorine levels with the bromine water, even if the bromine tested at zero?

Any insight appreciated.

[hymbaw]

Go ahead and start using Dichlor. It wont hurt anything using it in conjunction with Bromine. The Bromine will be "recharged" with each dose of Dichlor and the Dichlor will dissipate faster with Bromine present but you only have a couple months to go 'til you drain and fill.

[st18901]

I understand that the dichlor will actually convert to Bromine.
Shouldn't be a problem though.

[Vinny]

What they said!!

[tony]

Absolutely.

[Dr. Spa™ Ret.]

When bromine is added to the spa it's in the form of bromide ions. There is no test for bromide ions. When an oxidizer is added the bromide ions are converted into hypobromous acid. hypobromous acid is what a bromine test kit tests for. Chlorine is an oxidizer and will convert the bromide ions into hypobromous acid. As long as there's 15 ppm or more of bromide ions in the water, all the chlorine added is going towards converting bromide ions into hypobromous acid, none of it will provide a chlorine residual.

[ssbraun]

When bromine is added to the spa it's in the form of bromide ions. There is no test for bromide ions. When an oxidizer is added the bromide ions are converted into hypobromous acid. hypobromous acid is what a bromine test kit tests for. Chlorine is an oxidizer and will convert the bromide ions into hypobromous acid. As long as there's 15 ppm or more of bromide ions in the water, all the chlorine added is going towards converting bromide ions into hypobromous acid, none of it will provide a chlorine residual.

I thought I had read something like that here...does this mean that a complete drain / refill is required to ensure that the bromide ions are below 15 ppm, and the changeover to chlorine is successful?

[tony]

I thought I had read something like that here...does this mean that a complete drain / refill is required to ensure that the bromide ions are below 15 ppm, and the changeover to chlorine is successful?

For the most part that is correct.  The only way to be sure you have converted is a drain and fill.

[Brewman]

Which I will do as soon after I run out of bromine that the weather allows.  Anything in the mid 40's or higher would be tolerable.  
Thanks for all the advice.