Intermitently Connected Spa and Pool

[bbionicokie]

We have a new concrete inground pool with adjacent spa. The two bodies of water are separate except when we turn our spillway/waterfall on. Then water is pumped from the pool into the spa and the water overflows back into the pool via the waterfall. We designed the pool/spa this way because we wanted a retractable pool cover, and for the spa to sit higher than the rest of the pool. Also we wanted to be able to use the spa without retracting the cover over the pool if we did not intend to use the pool itself. The spa has a smaller manually removable cover. When the pool cover is retracted we wanted a waterfall for the sound of the water and to give the kids something to play in. One thing we did not think through and our installer did not bring up until the end of the project is how do we sanitize each body of water. We wanted everything to be saltwater, and were assuming that there would be 2 salt water chlorinators - one for the pool and one for the spa. But the installer has recommended for only the pool to have a saltwater chlorinator and for the spa to be the same saltwater supplemented with an automatic bromine feeder. The pool is approx. 24,000 gallons and the spa is approx. 1,200 gallons. Are there any foreseeable problems with his recommended setup? Any concerns with mixing two systems like this? How much bromine might we use if we run the waterfall often and thus turn over the spa saltwater frequently? If we turn the spa water over every day or maybe just every week do we even need any bromine in the spa at all? The installers response is, "Well you will just have to test the spa and pool water frequently and see what they each need." I'd like to have some idea of what to expect so we don't have to pay more to have either system changed out later.