Gjcon, I'm in Michigan, so I probably wouldn't even use my pool without a heater
I'm weighing in because I just replaced my gas heater of 15 years and will give you some tips if you decide that route suits. In your clime, you might enjoy a heat pump (depending on your electrical cost) or solar.
First off, gas is fastest in shoulder seasons here. We heat to a constant and then leave it run. At 88 degrees, that means the gas bill (in Mich anyway) is roughly equivalent to our winter boiler heat cost, a bit higher in a cold May or October. But we swim a lot at night (work long days) and i swim then again around 6 am or 7, and we have a footprint that makes us not want a cover, so for us its worth it.
We've found it's cheaper to just turn it on and leave it than constantly just bringing it up...small changes instead of large changes.
Now, the reason I was posting was to save you on purchase and installation. If buying gas, you need to figure out the biggest degree differential you'd have in shoulder season (eg mine is more than 30) to size the btus for your pool maint temp. In your clime, this isn't likely as important. You also need to figure out how many BTUs you might already be using of you line, and size your line right so that you'd never starve the heater. Post back if you decide to go this route DIY and I'll dig up the way to make the calcs -- I got em from an engineering site.
In my case that added up to 266 btus (if I went bigger, I'd have had to upgrade my gas meter to 1million btus and I didn't want to.)
I wanted a trouble-free heater without complexity in electronics, as less is more I find. A few people here directed me to the Raypavk with cupronickel heat exchanger (I'm swg and copper doesn't hold up as well). The comment from repair guys was they rarely need to work on them, and when they do, they're simpler to fix.
So the pool stealer quoted me $3,100 plus installation, which he subs, for this unit (replacement on same line, interior duct work already done etc.).
I instead went to
Swimming Pool Supplies, Pool Safety Cover, Swimming Pool Covers, Swimming Pool Pumps, Pool Pump Parts - INYOPools.com
(the owner is a member of TFP) and got the 266btu Raypak for $1600 shipped. I then paid an installer to install, install a zinc anode, adjust vent work, do gas line, electric and plumbing for $450 - which included the cost of the inline zinc anode (hydro tools).
So i was done and swimming again for a grand less than pool stealer wanted for the unit alone
