I have just gotten a 15 gallon brew pot and i am noticing i could be going through a rhino tank in one brew this adds $20 to the cost of brewing. Is this correct the water was about 45 degrees and took 3.5 hours before coming within 10 degrees of boiling. Bayou says with 3lbs of propane at 30,000 btus it could last 9.1 hours and with 55,000 about 3-4 hours. So with sparge and wert boil i can go through a tank maybe two. So is going electric really the best option to cut costs?