Or you could get a decent sized UPS system to protect and back up your computer stuff, and then use a long extension cord (if it not close to your tanks) to keep your tank pump running during an outage. A 10W power draw (2 of your 5W pumps) should last 6 or more hours with this one.
http://www.bestbuy.ca/en-CA/product/...999aefb993en02
Not a big discount, but free shipping right now.