Solar heater experiences?

[mustBnuts]

We have a 13 x 30 inground fiberglass pool. We have 2 of the 4 x 20's bought from Ebay. I put them on a flat rack next to the pool filter. I've been heating with them this season since 04/10/06. The kids went swimming in 82º water on Easter Sunday 04/16/06. 80º is my min. temp and I really like 84º - 86º. The pool was 83º today. We use a solar blanket when not in use and at night. I'd say that the solar panels are a little less than half the surface area of the pool. I use a small 1/16 hp pump, called a tiny might, to circulate the water through the panels for 9 hrs. a day when the sun is out. This pump uses about the same amount of energy as a 100 watt bulb. I can use the small pump because I don't need to lift the water up to a roof.
I figure we've extended the swim season by 6 weeks on the front end and 4 weeks on the back end, closing by Oct. 1st. We are located in Oklahoma at about 36º latitude.
The panels get sun from 9am- 6pm. The pool gets full sun from 9am - 4 pm.
Hope this helps. This has been my experience anyway.
The pool holds the temperature at night pretty good, only losing about 2º if it stays above 60º.