We have used solar mats since purchasing our pool in 2007, they've been great with no complaints however we feel our mats are coming to thier end and are considering a gas heater this year. We'd also like to be able to extend our season and maintain water temp of 88-90. We have a 27 foot round, approximately 17000 gallons. We are shopping now and would like some recommendations on size/manufacturer etc. and what we can expect in performance. We are in southern Wisconsin so really only get to use the pool the first week of June until labor day. I look forward to your input.