I decided to test my emperor 400 for total watts since most sites say this filter run 19.2 watts found that hard to believe so I bought a wattage meter now I run the short tube and have a large prefilter on it fill the tank up to the lip of the filter and ran it loaded with filter material for 2hrs and it read 7.8 watts! Then I tested my eheim 2217 it read 16.9 watts instead of 20.then I tested a 15watt bulb it read 14.5 so I know this meter is real close to accurate just thought I pass this along to save money on electric bills! Update:Put a new impeller in my emperor 400 now it reads 9.1 watts Still a far cry from 19.2 watts!