Stray voltage???

Nick Rose · Aug 9, 2019

So the last few weeks I have been getting this stinging filling in my fingers. I though at first it was the salt getting into my cuts. But I noticed it was only happening on one of our reef tanks. Then I noticed my candy Cane was not happy. The water parameters were good so I decided to do a 40% WC the coral perked up but it was unhappy again in a few days. So I checked for voltage and found out I had stray voltage in the water or I think it’s stray voltage. It’s only one pump doing it and it’s brand new from February. I have a ground probe coming today.

I have a few questions. Will the probe help in this situation? Is there a way to fix the pump(it’s a Mag 9.5)? Should I see if the company will replace it?

Yesterday I got a reading around 20 but it seemed to go down slowly and when I tested today it was showing 35.

(This was from yesterday)

WVNed · Aug 9, 2019

With the meter connected the same way turn the knob to the 200mA setting. You want to see something like .004. If you do a ground probe is for you. I you read 4 it is enough to trip a GFCI.
You are reading the current leaking into the tank. Induced voltage always has a tiny current value easily drained away with a ground probe.

Nick Rose · Aug 9, 2019

Don’t know if I did this right but I got 0. Is there a reason why the voltage would slowly decrease through the day. This morning it was 35 and now it’s 22.

WVNed · Aug 9, 2019

OK. Now do the same with the 20mA and 200uA scales. You should see some tiny amount of current.
My tank would read 14V with 4 on the 200uA scale if I remember right. I put a ground probe in.
A ground probe will remove the voltage you have though it isn't dangerous.
We have had several people post about tingling with non dangerous amounts of electricity in the tank. Some people are just more sensitive than others

Nick Rose · Aug 9, 2019

The 20ma is 0 and the 200ua jumps jumps around but the highest at the moment of testing was 1.1. For the fun of it I put the dial to 200m for I DC and it jumps around and the highest is 28. I guess thats coming from the Icecap Gyre. But theres no Voltage coming from that. Don’t know if that means anything.

WVNed · Aug 9, 2019

There is nothing much in your tank but some induced voltage.

Nick Rose · Aug 9, 2019

So does this mean the pump is not bad? It just seems odd. Because I have another 9.5 as the return pump and that one is fine and its I think 10 years old or so. The bad one is hooked up to the skimmer. I had already contacted the company and they said i could mail it in and they would check it over and if need be replace it. Also is it still smart to put the ground probe in since I already ordered it?

WVNed · Aug 9, 2019

If the pump is pumping water ok but only producing some induced voltage of the amounts you posted I would use the pump and add the ground probe. Your numbers will be zero then.
I have never had a tank that didn't show some voltage. Numbers I remember where from 14 to 36 volts.

There are 2 ways voltage gets in the tank. One is an insulation defect that leaks electricity from a conductor into a tank. I had this happen once when a pet chewed an electric cord. The tank tested line voltage.
There was enough current to shock me good. I am not talking about tingling.

The second type is induced voltage. This happens when something in the tank acts as an antenna for the magnetic fields produced by electricity flowing in wires. When given a path to ground you can measure this voltage from the tank. Through testing you can see that there is so little current these voltages are not dangerous. Sometimes you can reduce this voltage by rearranging how the cords are around the tank basically making the reception of the signal worse.