How many watts can a normal household circuit handle?

[C&C]

I know with my tank-
2 X 250 watt heaters
4 X VHO
2 X NO
6 X Maxijet 1200
Berlin turbo protien skimmer

My breaker trips once in a while for no apparent reason (15 Amp) I think it has to do when the heaters are on in the morning and if my lights come on at the same time it may cause a momentary surge, enough to trip it?

If i try to run my stereo at a high volume then I have to make sure my heaters are not on.

Using the vacuum is near impossible (not thats its a bad thing) If the heaters are on.

When I build my next house I will definately have 2 dedicated 15 Amp outlets wired to my tank location.

Chris.