fish disease?

All tank equipment is on a GFCI outlet. However, I live in an old
house. Most of the circuits are knob and tube style wiring. The
tank's circuit, as well as a few others, are updated wiring, but the
electrical panel is not grounded to anything. Is my GFCI useless?
What about a grounding probe? And is this the most likely cause of
the problem. Thanks for your input.


Who installed the GFCI? If it was a qualified electrician then there's
got to be a gounding line in the panel that it's conneted to.

mark h

Mark Henry wrote:

Who installed the GFCI? If it was a qualified electrician then there's
got to be a gounding line in the panel that it's conneted to.

GFCIs are frequently installed on ungrounded circuits for safety upgrades. It's
much cheaper than running a ground wire.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

wrote:

All tank equipment is on a GFCI outlet. However, I live in an old
house. Most of the circuits are knob and tube style wiring. The
tank's circuit, as well as a few others, are updated wiring, but the
electrical panel is not grounded to anything. Is my GFCI useless?

No. GFCI outlets are frequently used with obsolete wiring to provide the safety
equivalent of a grounded circuit. It will work just fine. If one of your pieces
of equipment were leaking current into the water, the GFCI would trip.

One more thing. Your electrical panel is almost certainly actually grounded to
something (I've never seen one that isn't). Prior to about 1970, it was common
practice to ground the box to the cold water supply line. These days, they sink
one or two heavy copper rods 8' into the ground and run a wire to them. It's
possible that the original ground wire was removed, especially if plumbing lines
have been re-routed.

What about a grounding probe? And is this the most likely cause of
the problem. Thanks for your input.

I use a probe on my tank, but I think it's unecessary if you have a GFCI (I put
mine in before I got a GFCI). From what I've read, the most likely cause of the
symptoms you describe is some sort of bacterial infection, but it doesn't have
all of the symptoms of the most common infections (for one thing, these are
usually white and cause tissue loss). Infections are hard to treat, since it's
hard to tell what antibiotic will work on your particular disease. You also
can't just dump a bunch of antibiotics in a reef tank.

Perhaps it's just old age?

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

"George Patterson" wrote in message news81If.23857$Eq.13398@trnddc02...
wrote:
If one of your pieces of equipment were leaking current into the water, the GFCI would trip.

You are correct, but it is important to know, it does not work like "all or nothing".

All GFCI are rated with a leak current detection threshold - they trip if the leak
current is bigger than a threshold and continue to work normally if the leaking
current is below the threshold. For many GFCI this threshold is set to the level
of 20-30mA. This is quite a strong current causing pain and musscle retraction
when applied to human skin. The purpose is not to kill a user only... but you
might still get zapped quite seriously and painful before the GFCI will trip.

And, what is more important in our aquarium applications: small currents
(below the threshold) continue to leak without being detected by GFCI...
So you can clearly have, lets say 5-10mA current leaking from your powerhead
failing insulation and your GFCI will do nothing to stop it. Will your fish feel it ?
We would need to ask them ;-)