I got a Kill-a-watt device on ebay for 25 bucks
It will tell you exactly how much each device costs to run.
Plug it into the wall then plug your equip into it and let it run for 24 hours.
Press the KWH button on it and it tells you how many Killowatts you used and then multiply by your electricity rate mine is 0.08 per Killowatt hour
My nano tank costs 0.10 per day to run. ($3.00 a month)
Including heater, lights, return pump, and ATO
Now granted I don't have big huge pumps, big heaters and 5 powerheads, MH lighting etc...
But hey get that device, and you can tell why your bill is so high.
My old fridge I found out was costing $45 a month, got a new fridge and now it's $13.00 a month!!
Neat little device that's cheap and easy to use..
http://search.ebay.com/search/searc...&sadis=200&fpos=95610&saprclo=&saprchi=&sass=
~Steve~