Our fiberglass pool was installed last May. We are still feeling the "sticker shock" of the cost of it. But I want a Hot tub! We have a perfect place for one. But there are two problems. After the pool cost, my wife and I are on somewhat of a "spending freeze" and we are no way, no how, going to buy a $8000 hot tub. The other problem, is that we most likely don't have enough power (amps) run to our pool shed, and I'm not going to have the electrician run more wire.
The good news; my pool man says my filtration system, and my raypak gas pool heater, has the capability to run a hot tub, in conjunction with my pool (but might need an additional pump?). The heater has two settings on it, one for pool, one for Spa, but I have no idea how to set this up. In fact, when we were ordering the pool, they offered us one of those fiberglass pools that has the hot tub "built in", on one side of the pool. But the cost was going to be $10K more, and my pool man even told me it might be better and cheaper to just buy a real hot tub.
My idea is to find a used hot tub on craigslist. There are literally dozens of them for sale, many under $1500. Then, I could retrofit the hot tub plumbing, to my existing filter / heater plumbing. If I can do this, it wouldn't require any new electrical permits, no additional load on electric panel (except maybe one water pump).
Is this is dumb idea? Has this been done before? I can't seem to find any plumbing schematics showing how to plumb this. I want to do it myself, and not pay my pool man to do it. If I have him do it, it might not be done till 2020.
Here is my equipment pictures below, showing my current heater, plumbing, etc.
1. I have one main pool pump that runs the pool and fountains, and one booster pump that does nothing but run the pool robot cleaner thing.
2. I have three drain lines form the pool: two bottom, one skimmer box
3. I have two return lines to the pool, plus two small fountains.
I'm pretty handy and feel confident I can do it myself, but I don't understand how the plumbing will look. How can the filter run both a hot tub and the pool at the same time, without mixing water? Or maybe it can't do it at the same time, but one at a time? I would be ok with heating only one at a time, but I think I would want water flowing on both, at the same time. Maybe that water flowing isn't "filtered" at the same time, but at least moving.
I'm reaching out to you guys to see if anyone has done this before and maybe you know how to do it? I don't need any "hand holding". I'm just looking for your opinions if I should try it, and if so, do you have a basic schematic of how it is done with my current equipment?
And these are the choices for hot tub location: