Not sure what normal sized exactly means in your case, as you don't mention the size of your tank. I have heaters ranging from 25 watts to 300 watts on tanks ranging from 10 gallons to 110- And according to manufactors specs, that 300 watt heater is underpowered.
Your heater will be the biggest thing, and it's just a guess what it is- maybe 200 watts? Heaters depend on tank size, and you didn't give your tank size. You have two emperor 400's, which makes me think 100+ gallons. You mention 2 36 inch lights, so it's either a 3 foot or 6 foot tank?
Filter- I have no idea. You can contact Marineland via their website (
www.marineland.com) or by phone- Their number is on the website. You might also check your filter itself- I just checked the filter on my 10 gallon, and it's labeled 5 watts. Check near the motor housing, maybe on the bottom.
A 3 foot light also is not enough of a description. If it's a single tube, each light is probably 25 or 30 watts. The light bulb probably has it printed on it.
If it's a CF, it could be 96 watts per light. The label on your light fixture itself may not be accurate- That'll be what the ballast is rated. You want the number off the light bulb.
Finally, your air supply- Again, not a clue. I just checked my Whisper 60, it's labeled 4 watts. Check the air supply itself, it's probably labeled.
For a larger tank, when the heater is actually turned on, 400 watts could easily be correct. Remember, your heater and lights don't run 24/7. Or, at least, they shouldn't.