black bottom?

Uh, maybe by .1 degrees

You can use a liner designed to trap heat for a little warmth, or you will have to go with a solar or regular heating system to actually bring the temp up

Whatever the average low temp (between 60 to 90) was for the past 3 nights is generally what the pool temperature will be.

Wow, a black bottom makes that little of difference?? So then any idea how much it would cost for a solar install to heat a pool this size??

About tree-fiddy, sorry but it has been years since I even looked into them in AZ & I couldn't even hazard a half way decent guesstimate now

You might want to start here http://www.builditsolar.com/Projects/PoolHeating/pool_heating.htm & go from there

It will take about 238 square ft of solar panels to do the job efficiently ( 1 sq ft panel per sq ft pool surface area). Suggest you call around. Most of the time your pump will have to be upgraded to handle the increased head pressure to get it up to the roof, thru panels and back. Check into that as well.