Wiring advice/help needed (voltage in tank)
 

I posted a couple weeks ago about checking voltage in tank water here. I had what i thought was i minor problem, got zapped with my hand in the water, checked with voltage meter got some readings, figured it out..It was a T5 light covered in salt creep and i bypassed the ground prong on the plug. plugged it into proper socket. Lesson learned. I installed a GFCI just after that happened and put a rid-volt in the tank. No more readings. Fast forward to last night. Zapped again :(. The rid-volt has a crappy suction cup and fell out. Put the grounding probe back in and still felt the zap.Tested the water THIS time on the proper voltmeter setting 0-200v AC (last time i was using 0-20v DC, oops) 54 volts!

Unplugged everything one by one and the voltage dropped bit by bit for every device. Its not one thing but everything?

With everything unplugged i get 2.7 volts (this is literally with NOTHING in the tank plugged into a power source)
with the lights plugged in it goes up to 4.5v
+ skimmer 21.6v
+ heater 32.4v
+ koralia powerhead 40.8v
+ aquaclear filter 54.0v
+ rid-volt and it drops to 4.0v

Theres more to the numbers but too much wiring stuff and i get a headache. Did i install the gfci wrong? ive tried 2 separate powerbars and get the same basic results. Its a super simple tank setup, if someone is good with this stuff and can fix it i'll pay in beer, frags, money, whatever. The fish and corals dont mind but i don't wanna get zapped again

Blah :redface:

One more thing. In the meantime until this is sorted should I leave the rid-volt out and subject the tank to 54 volts OR put the it in and ground the water to 4.0v. I don't know what's better

This is actually a very complex situation. I will assume that your GFCI is installed correctly as they are fairly straight forward. What you are dealing with is what we call Induced Voltage. Everything electrical generates an electro magnetic field. When this field interacts with something that conducts electricity (like salt water) a voltage is created. The Ballast in your light fixture, and the fluorescent lamps themselves cause this, as do all of the motors in your tank. Skimmer, powerhead, filter.. and even the power flowing through the heater all act to create a voltage in the tank. This does not cause the GFCI to trip because there is no loss of power by any of the items plugged in. The voltages you read are electrical potential differences between the water and your homes ground, providing that is where your other meter lead is. The 2v you read with nothing plugged in could be from any other nearby electrical device or could just be residual not quickly dissipated when you unplug everything, or other things.

As the tank sits without rid volt, there is a potential in the tank but with nowhere to flow there is no current flowing and no real risk to your tank inhabitants. You being shocked is another matter, when you touch the tank you become that path for electricity to flow, something as simple as wearing shoes while working in tank can actually eliminate this. Adding the rid-volt will give the voltages induced somewhere to go meaning you shouldn't get shocked, it does mean however that now your tank inhabitants constantly have electrical current running through their habitat.

Tricky decision. The 50v is not likely to cause any real harm to you, but if your standing bare foot on a metal drain in a puddle of water the potential is there, i generally only notice it if i have a small cut on the finger in the tank, and I'm touching the stand

As a read back through this i realize it may be more confusing than helpful. Short story I guess, unfortunately there is likely nothing you can do short of disconnecting everything electrical anywhere near your tank and then stirring the tank with a wooden spoon for flow and the sun for light. But I wouldn't stress out about it too much. If your worried about the zap put the rid volt in just keep an eye on your fish to see if it seems to affect them.

Hope that helps a bit, if not let me know and i will try again

I have a skimmer, return and chiller pumps, 3 x 200w heaters, and 2 maxijets in my sump.
I only get 0.07 volts, so all my gear is still waterproof.
I have a crappy maxijet in my ato and it leaks 4.5v - no big deal.

Looking at your list I'd suggest you start replacing hardware as the units that are leaking voltage will eventually get worse and fail, probably blowing your gfci and turning the whole system off.

And I'd leave the probe out of the tank unless you plan on working in it.
I've never liked the idea of subjecting the critters to voltage with a probe, and only use probes in my tanks to protect me in case of a sudden failure.

I thought having the probe in makes it so the fish are not affected by the voltage?

Pretty sure, i left the yellow tape on an followed directions

LOL had no plans on that

Could you try explaining this part a bit more?

I really appreciate your reply! Its helped some :)

Good idea, i will probably just shut this tank down and build something bigger and better. :) Really weird that all the equipment contributes, Skimmer is 3 m/o reef octopus, heater 1.5 y/o aqueon pro, koralia 6 m/o. The filter and lights are at least 3 years old though.

I read this somewhere on RC last week, if its true the fish don't look to react any different with or w/o the probe

The probe completes the circuit to ground, so it is now flowing through the water

Bryant it does seem a bit odd that the newer equip is acting up ...

When you tested, you put the black/negative probe in the 'D' shaped socket in your outlet, and the red/positive probe in the water ?

Maybe try individually testing hardware without the lights

Yes, the red positive probe was submerged in tank water and the negative was in the 3rd D shaped hole in the wall, and also tried a power bar ground hole with no difference.
Not sure if this could be related but something strange I noticed was testing the GFCI wall plug I get 120 volts each, but if I test the power bar plugs (2 y/o Coralife digital power centre) and get 39-40 volts for each plug.

I will try each unit in its own when I have time this afternoon and post results

Something still doesn't sound right here. Did you test the ground in the box before you installed the gfci?