One thing I did was to put a garden variety HVAC thermostat
(weatherproof box) in line with the pump, via a contactor, so it only
runs if the outside temp is high enough to help you. If your pool is
not covered you won't be able to get much above ambient air temp, no
matter how many panels you have. The thermostat is about as good a
predictor as a lot more expensive solution will give you and easy to
adjust for the desired result
A solar pool heater works off heat absorbed from sunlight, not from
ambient air temperature. We had a solar domestic water heater whem I
was in Pennsylvania. It produced a maximum of 177 degrees F domestic
hot water during the summer. It was no where near that hot outside.
The solar pool heater should have all the controls it needs built in.
When I did solar pool heaters, we used FAFCO brand, they worked great.
As far as the pump wurking in your application John, You would have to
look at a pump curve. The pool heater manufacturer can tell you how
much flow you need at what head to push through their pool heater
panels. Since pool heaters are using water open to the atmosphere, you
need that dynamic head plus the head for the existing piping plus the
15 feet vertical static head for the panel height. So if you have a
low head, high flow pump, it may not work.
But you can always try it any how if you wish.