Recommendations for 18K gallon above-ground pool heating

Hello there my permie friends,

I was wondering if it's realistic to use an RMH to heat my 18K gallon pool. I'm in Virginia, so we get hot summers.  Having the mass portion would be useful for the sitting area.
The pool is meant to be therapeutic for my wife and my mom, so they can get in shape, so extending the season from April to Nov/Dec would be helpful.

Last year, with the pool cover and the warm summer, I didn't need to do any heating as it stayed above 80' F betwixt June and Sept.
I have 1.5" pipes running off of my pump with Y's and valves that can feed the solar panel and two of my coil heating devices without a decrease in flow rate.

I had tinkered with solar, but didn't build enough panels (200' of irrigation line on a plywood frame). That only netted a degree since it was fall and the sun was usually below my neighbor's trees.

I tried an upright 55 gallon barrel with 1/2" pipe wound around the inside, and did get some limited success when the fire was at its hottest, at best was 50K BTU (it was about a 30' F rise with 2.5 gpm flow, iirc) (based on Soloengineer via YouTube)

I laid the barrel on its side and got better results (8' exhaust at top was clear) with a 5' F rise in 24 hours using compressed sawdust logs, but it required tending ever hour or two.

Then I tried the Aussie rocket stove with brick and a coil of copper in a rounded chamber, but it was November and simply didn't warm the water.

I can send pictures if interesting (even as a "what not to do" instructional.

So the question boils down to "is is possible" (Giorgio Tsoukalos  ; ) to build one that could generate 200K BTU or more (what the pool heater sizing sites recommend), so I don't have to resort to installing a propane tank and heater?

I did contact one of the advertisers here, but it would be pretty expensive (over 5000 pounds), not counting shipping from UK.
I've gone through most of the threads (if not all) and trolled the Internet and YouTube without finding any that work for my requirements.

Thanks for any recommendations, including DVDS and/or books.  It was a bit overwhelming and I wasn't sure if any of them would address this.

I know a guy on Vancouver Island, Canada who uses a heat pump to heat his pool. It's a mild climate. Just one more option to consider.

Douglas Alpenstock wrote:I know a guy on Vancouver Island, Canada who uses a heat pump to heat his pool. It's a mild climate. Just one more option to consider.

Thanks Douglas,

I had considered a heat pump, but my understanding is that they only work to 55 degrees, so if we get a a cold night, there will be a lot of heat loss with no recourse. We will get colder nights, but still have it 75 the next day, so need something that can handle at least to the 40's.
The other issues are cost in that they are around $2000, which doesn't count the wiring, and possible panel upgrade to support. I would go with propane before heat pump I think.