How much cost to maintain a outdoor pool a year?

Question:

Answers:
Starting the season - $150
Closing at end of season - $100
Maintaining for 3 months - $150
Equipment, seals et. al. (replacement) costs $50/year
Having a pool I can use ANY time & don't have to share/pay annual fee (about $200 here) - PRICELESS

That's just chemicals/parts & not electricity. Electric cost hard to estimate as pool season = AC season!

My pool is in-ground 16' x 36'. About 20,000 gallons