Hydrotherapy with a hot-tub and a swimming pool

What's the best way to go about doing hydrotherapy with a bromine-disinfected hot-tub and an outdoor underground salt-disinfected swimming-pool?

It's very cold outside, so the pool water is probably around 48 F, and the hot-tub can be adjusted.

I'd like to jump in completely and get the water over my head. I hope I do not pass out from shock or something. This should be very intense. I have access to these facilities just for a few days. Is it OK to do it day after day for as long as my body feels up to it?