Shared Heater/bromine And Chlorine

[JAM]

I have a 37,500 gal. pool and a 2500 gal spa that share a Pentair 400 Gas Heater. It is newly constructed and the pool builder piped it with bypass valves to get each to heat. In other words, only one will heat at a time.

A series of valves are turned on and off to direct the water from the pool OR the spa to the heater. I also have to go to the heater and press the button that changes to Pool or Spa mode.

Question 1 is more a statement. Is is quite annoying having to make these changes to get the heat where I want it and when I want it. When the pool is heating to 90 Degrees, the spa of course will loose heat from evaporation, aeration. Seems like a horrible design.

Question 2. I use chlorine in the pool and bromine in the spa. I am certain that brominated water enters the pool from the residual piping and heater core when I switch over. Like wise, I am sure chlorinated water is getting into the spa. Anyone see any issues here? There is about 10 feet of 2" pipe on both the return and inlets from each bypass.

Thanks for your comments,

JAM

[chem geek]

JAM,

I can answer question 2 for you. If chlorine from the pool gets into the brominated spa, that is not a problem. It will just reactivate any bromide to bromine and in fact chlorine is often used as a shock for bromine spas though non-chlorine shock is another alternative. So there is no problem with chlorine from the pool getting into the spa.

As for bromine from the spa getting into the pool, this would be a problem if it were large quantities since it would eventually turn the pool into a bromine pool with the chlorine only regenerating bromine (bromine is sensitive to sunlight and doesn't bind to CYA to protect it as much). In practice, however, the quantity is probably small enough that the bromine eventually dissipates from the pool (it eventually outgasses).

Richard