I got the Centameter tonight, what a cool device!!! Even happier coz I got it for $50 on Trademe, usually around $140 new The main display is a "cent/hour" costing on your power. Right now (with the dryer on) its showing 42.8 cents/hour (that's based on 11.9cents per kw - this is what Genesis charge during the day and about 9 cents per kw at night. You can only specify a single per kw $ rate so I opted for the day rate since thats when most of the power is used) Incidentally, I turned the Dryer off and it drops to 21 cents/hour! Thats 20 cents/hour to run a dryer (and the toaster is about 10 cents per hour!) Funny these figures dont seem much, but when you start adding it up it costs quite a bit over a month.
Anyways, I did a test on the tank. At 10pm when the halides went off (3 x 150W), it dropped by 7 cents/hr. Halides are on for 10 hours a day so thats 70 cents a day or $21 a month (however I still have to add 4 x T5's at 52W each so would guesstimate another $10 a month on top of that) I did the same for the sump room plus closed loop and streams and it dropped by around 6 cents/hr. At 24 hours a day thats $1.44 a day or $43.20 a month. So far a total (including T5's when they go in) of about $74 a month. This price does not take into account the chiller or heaters (they are currently off as the tank temp is stable at 25 degrees) It also does not take into account things like the lighting over the refugium (currently on), topup pump and also the zeovit pump (which alternates on 3hrs, off 3hrs - not even sure whether it was on or off when i did the test)
The other thing to look at is the way power companies charge you - they usually do a "per unit" + "per day" costing. For example, 11.9cents per kw at day, 9.0 cents per kw at night and 100 cents (roughly) a day. The day rate is charged no matter what, so you can argue you have to pay this anyway and should not be included in the overall tank power cost.
The Centameter is definately a cool device and its very interesting to see what consumes the most power. I've been turning different devices on and off all night to see what effects it has The TV takes up bugger all power which I was surprised at. As usual, heating type devices cost most such as toaster, dryer and when shower goes on, hot water cylinder heats up cents/hr usage goes up quite a bit. Oh, and it also shows you temperature, humidity, kW's currently being used, Amps currently being used and greenhouse gases emitted (if you're into that sort of thing )