Pool/Spa water swaps


Jun 6, 2011
French Camp, CA
I have a borate pool with SWG, and standalone spa with small, drop-in SWG. My normal practice has been to replace spa water with pool water, pumping spa into pool & vice versa. Simple and fast. I recently did some repairs to spa, and decided to start using spa frog bromine and mineral cartridges, along with new ozonator. Now I'm about to do another water swap.

My question: will I mess up pool chemistry with bromine & spa minerals? Maybe i need to pump spa into field and stop using bromine cartridge. I assume mineral cartridge will not hurt---contains silver chloride and calcium carbonate. Appreciate thoughts on this.


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
DO NOT ADD that spa water to the pool. The silver isn't an issue but the bromine is. If you add bromine to a chlorine pool, the bromine will cause a constant FC demand because chlorine converts bromide (spent bromine) back into bromine. There is no way to separate the concentrations of bromine and chlorine in the pool as the DPD test simply measures total halogen concentration. It won't matter much at first given how much smaller the spa volume is BUT over time you'll just screw up your pool with the silver and bromine. Eventually silver can become a problem in a chlorine pool leading to scale and staining which is nearly impossible to remove.

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