[newhit]

Not to sure that ppl need a relay at all?
My Eheim is wired straight to the mains plug on the comp psu (thru a service switch) so that when the wall skt is switched on then the pump starts before i go anywhere near the computer. I do have the service switch wired inside the case for testing/filling use but this is left in the "on" position so my pump is always switched on or off by the wall supply or in my case the multiplug thats plugged into the wall. Takes the doubt away completely, it seems to me, and the juice is flowing before the comp starts up which can't be bad.

Also, shouldn't relays be wired with arc suppression in the circuit to inhibit the back emf.

I'm not saying it's wrong to use a relay , just that it might be overkill