I am trying to figure out how much it will cost to heat my pool for a weekend, to get a ballpark estimate. I have a gas heater (Purex Triton Minimax 250) and trying to see how much I am in for before firing it up. Here is my data:

pool size = 15' x 30'. Water temp = 70, would like to have it 90. From this website it says I need approx 108,000 BTU's to raise the water temp. 20 degrees for this pool:

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I assume this means it takes 108,000 BTU's to get the temp up 20 degrees, at that point the heater turns off (and the pool starts to cool

From the below website it says there are 1080 BTU's per cubic foot of gas:

http://www.appleheating.com/heating/fue ... calculator

This gives a requirement of 100 CCF.

In my area gas prices are running about $0.7 / CCF from below:

http://www.centerpointenergy.com/servic ... prices/HO/

That would be a total of 100 * 0.7 = $70, to heat my pool by 20 degrees. Or to raise it 10 degrees, $35.

1. Does this seem legitimate? Am I missing any basic steps here?

2. Once pool is at 90, how much does it cost to maintain this temp for 8 hrs, or for 24 hrs?

3. My heater is rated for 250,000 BTU's per hour. How can I determine how long it would take to raise the temperature of the water - eg. 1 hour, 8 hrs, etc?

Thanks for any help you can provide. My next step is to research solar blankets