Metal halide lights trip GFCI all of a sudden

In article ,
says...
You have one of 2 things going on. Either your GCFI is getting more
sensitive which is causing it to trip. Or you have a cap going out on
one of your ballasts. What you should do to check is try only running
one halide at a time and see if it still trips. that way you can
isolate it down to either one ballast or the GFCI.

One suggestion I would have for you is redo your tank wiring, having
everything on the same GFCI is very dangerous for your tank. If
anything goes wrong you loose all power to your tank, which normally
means you loose all life in your tank after a while. Move atleast a
couple of filters/water movement devices to another circuit so that you
will not loose everything.

Kim

Hi Kim-

Thanks for some good advice. When I set up the tank years ago, I had to
run a circuit to a relatively remote location, and just ran one. After
some time, it occurred to me that splitting it over two circuits would
have been better for the reasons you brought up. But, with a 90 gallon
tank in the way, it was harder to do at that time than I was willing to
handle, and since it worked well for years I eventually just let it be.

The tank is highly redundant, by design. In addition to the main filter
(a big old Eheim, which presumably died the second time the power was
out for~16 hours), there's an internal power head with sponge filter,
which doesn't die when the power goes out. Lots of plants, not too many
fish, etc.. The main filter probably represents 50% of the
biofiltration capability in the system.

So, the real threat is the power coming back on after a prolonged outage
dumping nasty dead-filter water back into the tank. When the filter
went dead, I manually unhooked it and let a few gallons run through to
waste.

Meanwhile, I'll see about testing the MH systems individually if
possible. They may be connected inside the metal box; not sure if they
are intended to be operated separately. And, it's an intermittent
problem, so it will take a while to sort out.

If that doesn't do it I'll swap the GFCI.

Thanks

Marc