Voltage in tank?

[jiggysmb]

Thanks for all the input. We wont be testing with fingers anymore since we are aware of a problem. I think I will need to have an electrician come take a look to rule out an issue with the main outlet.

I have spent some time testing and have these results which still seem a bit odd. I did a test from a cup of fresh water to a cup of sale water and got 8v, so salt water must trick the probes in some way.

40 Gallon tank - 38v from water to outlet ground
unplugged Ocean revive light, dropped to 8v
unplugged 1 of 2 heaters, dropped to less than 1v

75 gallon uses a batter back up so I tested with the power strip plugged into the wall vs battery and receive same results below. - 34v from water to outlet ground
unplugged sump heater - dropped to 28v
unplugged pump - dropped to 22v
unplugged protein skimmer - dropped to 14v
unplugged ecotech power head - dropped to 7v

I dont understand how both of my tanks have had this issue assumably for their 18 months of life and we are just noticing. Wouldnt the voltage damage corals? The ecotech power head electrical connection is outside the tank so I dont understand how unplugging that would have a drop. All my devices have 3 prongs so everything should be grounded.

 

[Dburr1014]

Thanks for all the input. We wont be testing with fingers anymore since we are aware of a problem. I think I will need to have an electrician come take a look to rule out an issue with the main outlet.

I have spent some time testing and have these results which still seem a bit odd. I did a test from a cup of fresh water to a cup of sale water and got 8v, so salt water must trick the probes in some way.

40 Gallon tank - 38v from water to outlet ground
unplugged Ocean revive light, dropped to 8v
unplugged 1 of 2 heaters, dropped to less than 1v

75 gallon uses a batter back up so I tested with the power strip plugged into the wall vs battery and receive same results below. - 34v from water to outlet ground
unplugged sump heater - dropped to 28v
unplugged pump - dropped to 22v
unplugged protein skimmer - dropped to 14v
unplugged ecotech power head - dropped to 7v

I dont understand how both of my tanks have had this issue assumably for their 18 months of life and we are just noticing. Wouldnt the voltage damage corals? The ecotech power head electrical connection is outside the tank so I dont understand how unplugging that would have a drop. All my devices have 3 prongs so everything should be grounded.

Are you on a gfci also?

 

[LARedstickreefer]

Measure the current flow. It’s probably either zero or so close to zero, it might as well be. You’ll see voltage on your meter all over the house due to electric fields from just about everything.

 

[BaliReefBox]

i am not sure if it has been mentioned but try the hot water service for the house...they are notorius for stray voltage

 

[jiggysmb]

I

Measure the current flow. It’s probably either zero or so close to zero, it might as well be. You’ll see voltage on your meter all over the house due to electric fields from just about everything.

I am not sure how to measure flow, is that a setting on the multimeter? Are you saying if it is low, then this would all be normal? I just dont get how every device is adding to the voltage reading, even devices not under water.

 

[LARedstickreefer]

I

I am not sure how to measure flow, is that a setting on the multimeter? Are you saying if it is low, then this would all be normal? I just dont get how every device is adding to the voltage reading, even devices not under water.

It’s a setting on the meter. If a device has ruptured in the tank, you’ll see current flowing to ground. Stray fields (this is what I’m thinking that most see) won’t be able to provide much current (5mA will stop your heart).
-Matt

 

[jiggysmb]

I had an electrician over today that confirmed there was no issue in the outlet and it was properly grounded. He recommended a GFCI but could not explain why every single device caused a drop in voltage. He said the GFCI outlet would had protection but would not stop the voltage from reaching the water. I have ordered the grounding probe, so hopefully that helps. mA measured .4.

As a test we unplugged everything that was submerged and still had around 10v in both tanks. Unplugging the lights and power heads got voltage down to 0.

Currently, I removed the 2nd heater from both tanks, cobalt aquatics, and the voltage in both tanks is measuring a bit lower, 29v & 26v.

 

[LARedstickreefer]

I had an electrician over today that confirmed there was no issue in the outlet and it was properly grounded. He recommended a GFCI but could not explain why every single device caused a drop in voltage. He said the GFCI outlet would had protection but would not stop the voltage from reaching the water. I have ordered the grounding probe, so hopefully that helps. mA measured .4.

As a test we unplugged everything that was submerged and still had around 10v in both tanks. Unplugging the lights and power heads got voltage down to 0.

Currently, I removed the 2nd heater from both tanks, cobalt aquatics, and the voltage in both tanks is measuring a bit lower, 29v & 26v.

So that’s 0.4mA from tank to ground prong? That’s probably within the error of your meter unless it’s a very nice meter I’d say that confirms that you’re just seeing the effects of a conductor (your tank full of salt water) within reasonable range (several feet) of an electric field (all electronic devices create an electric field when operating).

For fun, hold one meter probe in your hand and the other up into the air near some OH primary lines outside your house.