Matt wrote:

Dont buy an above ground pool.

EZ-Set pools seem nice, with the air doughnut at the top... 12'x36"
for $98, 14'x39" for $159, 16'x42" for $218, 18'x48" for $297, at
Wal Mart, including a ladder and pump and filter.

They might last a long time, away from people and out of the sun.

We might put a 12'x3' pool inside a 16'x16'x8'tall greenhouse with 5 $7
doubled 1x3 bows on 4' centers and stretch 2 $20 16'x25' poly film layers
over a $20 layer of 80% shadecloth over the bows and trickle water between
them with Grainger's $157 4RD12 pump, collecting 0.8(620+1000)8'x16'
= 165.9K Btu and losing about 6h(130-34)201ft^2/R1 = 115.8K Btu on
an average January day in Phila, for a net gain of 50.1K Btu/day.

If it supplies 50K Btu/day over 5 cloudy days and 250K = (130-110)P,
it needs P = 12.5K pounds of water, 12.5K/62.3/pi/6^2x12 = 21" deep.
We might float a 10'x1" foamboard disk on top that supports a 300'x1"
$60 HDPE pipe in a flat spiral to heat water for showers, and surround
it all with 2' of mulch or bags of dry leaves.

Nick