It depends how you want to do it.
You can buy a relatively cheap plug monitor from CT for $20. You'll have to measure things on a device by device basis or you can measure full power bar at once but depending on the size of the tank probably not the total at once unless your tank is small or you buy multiple monitors.
http://www.canadiantire.ca/AST/brows....jsp?locale=en
Or you can buy a whole house monitor which you could also connect just to the circuit the tank runs on.
http://www.ebay.ca/itm/Real-time-Wir...ht_9118wt_1159