jv your post interests us as we had considered that sort of heating. From other threads I assume the solar heater typically isn't that effective though we must assume there's a matter of its size so how big is yours and more important perhaps, where do you live

Intuitively 28 lb seems on the high side but I can't believe the filter significantly slows flow though you will doubtless hear from others

i've had my pool up to the high 80's in the past. I'm in San Jose, CA 95118. I don't know how to quantify the size but I have 8 BIG panels on my roof and can normally get 80+ water temp.

thanks again,

~jv

As to size of panels I recommend reading at the U of Central Florida sponsored Florida Solar Energy Center.

http://www.fsec.ucf.edu/en/consumer/solar_hot_water/pools/index.htm

As to PSI values, solar will either require more power (variable speed pump) or reduce flow rates (single/two-speed pump). The amount will value according to number of panels, size and distance of piping, height of panel install, etc. Overall, they are more electrically efficient than a heat pump (for comparable cash outlays).

how many gallons is your pool?

jvmagic, many factors affect solar heating. We have 1:1 ratio sq footage panels to surface area and we keep the pool thermostat set at 91 degrees. Now that we have cooler nights it is very important to have a solar cover on the pool at night time. Last night the temp went to 50 degrees and this morning my pool temp is 86 degrees. The pump will run about 4 hrs today to get the temp of pool to 91 degrees. 28 psi sounds a little high. My pressure is 22 psi with solar on. I would think that a higher psi would have less flow but I am not sure what the ineffiency would be. What does your psi normally run? Are you using a solar blanket?
BTW we are in Jackksonville Fl.
Hope this helps

How cold are your nights? You can loose alot of heat overnight if it is cold outside. Use a solar cover at night and you won't need to play catch up with heating. I am in Phoenix and can gain 6 degrees on a 90 degree day (75% coverage), but loose 3-4 degrees overnight.