Stray Voltage

[GreenreefSC]

So I tested my aquarium with a multimeter and got a reading of 0.2. I only have a heater and powerhead in my tank so i unplugged both and it was still reading 0.2, whats the deal here? Is .2 even dangerous?

 

[robbyg]

So I tested my aquarium with a multimeter and got a reading of 0.2. I only have a heater and powerhead in my tank so i unplugged both and it was still reading 0.2, whats the deal here? Is .2 even dangerous?

Nope not dangerous and is probably just an erroneous reading from the meter. If you have stray AC voltage it will read much much higher.

 

[Terri Caton]

You’ll feel it when you stick your hand in the water too.

 

[GreenreefSC]

You’ll feel it when you stick your hand in the water too.

Nope not dangerous and is probably just an erroneous reading from the meter. If you have stray AC voltage it will read much much higher.

Any idea on how high the voltage would have to be to start killing hermits and snails?

 

[Paul B]

110 volts.

 

[Brew12]

There are two types of voltages you can get in your tank. One is an induced voltage which is relatively harmless imo. Mine can run upward of 28V and I know people who have it much higher. This is caused by electrical induction or capacitance due to current carrying wired and devices near the water. If you take a 100ft extension cord and coil it around the outside of a bucket filled with saltwater, the water will read very high voltage.

The other voltage, and a much bigger concern, is a fault voltage. This means a copper or aluminum conductor that should be insulated is making contact with your water. I feel that even this type of voltage is unlikely to directly hurt the fish although it may bother electrical receptors and cause HLLE. My biggest fear for livestock is the contamination that can be released in a tank. Energized copper will corrode quickly in salt water. If heat is generated, you could release toxins from rubber, plastic and other material. Just bad things.

This is why all of my submerged equipment runs on GFCI and I use a ground probe. Odds are, with 0.2V, you already either use a ground probe or have a titanium heater which acts like a ground probe.

 

[Multra]

There are two types of voltages you can get in your tank. One is an induced voltage which is relatively harmless imo. Mine can run upward of 28V and I know people who have it much higher. This is caused by electrical induction or capacitance due to current carrying wired and devices near the water. If you take a 100ft extension cord and coil it around the outside of a bucket filled with saltwater, the water will read very high voltage.

The other voltage, and a much bigger concern, is a fault voltage. This means a copper or aluminum conductor that should be insulated is making contact with your water. I feel that even this type of voltage is unlikely to directly hurt the fish although it may bother electrical receptors and cause HLLE. My biggest fear for livestock is the contamination that can be released in a tank. Energized copper will corrode quickly in salt water. If heat is generated, you could release toxins from rubber, plastic and other material. Just bad things.

This is why all of my submerged equipment runs on GFCI and I use a ground probe. Odds are, with 0.2V, you already either use a ground probe or have a titanium heater which acts like a ground probe.

Wouldn't measuring amperage for the second scenario be the way to go? If you had an electricity exposed to the water amperage should be "high" correct?

 

[Dom]

Tell us; how are you measuring the voltage?

The negative probe should be in the ground of the wall outlet and the positive probe placed in the tank. The meter should be set to AC volts.

 

[Brew12]

Wouldn't measuring amperage for the second scenario be the way to go? If you had an electricity exposed to the water amperage should be "high" correct?

I wouldn't bother. If it is an induced voltage the current will quickly drop to effectively 0 amps. If it is a fault voltage, it will blow the fuse in the meter.

Tell us; how are you measuring the voltage?

The negative probe should be in the ground of the wall outlet and the positive probe placed in the tank. The meter should be set to AC volts.

When measuring AC volts or current, the polarity of the probes doesn't matter. It's only important to get the correct polarity when testing DC. Otherwise, I agree.

It can also be handy to run an extension cord to where you are testing if there isn't a receptacle convenient and use its ground for testing.

 

[Quietman]

If it's "fault" voltage - meaning there's a path to ground for current - then 30 AC volts can kill you (I'm less worried about the corals). This is because under the most extreme circumstances your body resistance could be as low as 300 ohms (granted this is extreme but your hands are in saltwater)...that mean a current of 100 mAmps - which can be lethal.

Ok scare statement aside (and be scared - this is why I always recommend GFCI and grounding wires), .2 volts isn't anything to be worried about, it's likely stray from inductive sources...measure your refrigerator to ground sometime.

But GFCI and Grounding Wires - always!

 

[Dom]

When measuring AC volts or current, the polarity of the probes doesn't matter. It's only important to get the correct polarity when testing DC. Otherwise, I agree.

Agreed; polarity doesn't matter. Sometimes people reverse the probes and get a "negative" reading. Trying to avoid explaining that.

 

[Mical]

To OP: do you have a return pump & skimmer? Both of those are usually AC powered also - maybe you minute leakage is there, try unplugging them once while testing.

 

[GreenreefSC]

To OP: do you have a return pump & skimmer? Both of those are usually AC powered also - maybe you minute leakage is there, try unplugging them once while testing.

I do not have a sump, and i have an air powered nano skimmer. So it only has an airline in the water.

 

[GreenreefSC]

Tell us; how are you measuring the voltage?

The negative probe should be in the ground of the wall outlet and the positive probe placed in the tank. The meter should be set to AC volts.

I have the negative probe placed into my power strip that all the equipment is using.

 

[Dom]

I have the negative probe placed into my power strip that all the equipment is using.

May I suggest you not go through the power strip...

I don't know that it will make a difference, but I would be curious to see if your readings change when going directly to the wall.