Last year my pool was freezing by the 2nd week of October - due to the cold nights. A mate put me on to Tropical Solar Fish - Liquid Solar Swimming Pool blankets and they are brilliant apparently.
Basically its a plastic tropical fish, you snip the corner of a fin off and drop it in your pool where it bobs around happily for a month.
It works by dispersing an active ingredient in isopropyl alcohol that forms a one molecule thick layer on the top of your pool. This tiny layer reduced heat loss from evaporation by up to 40%.
I look forward to seeing the results as the evenings get nippy and shall keep you posted.
If you want to know more the UK distributor's site is here
http://www.hayward-air.co.uk/solar_blanket/index.php?u=426182556
