Using ground probes in aquariums

marvelousone

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I had my hand in the tank today. While my hand was in the water my shoulder hit my light fixture. I got a shock. It is a 8 bulb t5 fixture. Does that mean my light fixture has a short even though all bulbs are working.
 
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Brew12

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I had my hand in the tank today. While my hand was in the water my shoulder hit my light fixture. I got a shock. It is a 8 bulb t5 fixture. Does that mean my light fixture has a short even though all bulbs are working.
More than likely it is the other way around. You probably have something faulted in your tank and the light fixture provided a path to ground. I'm assuming you don't have a ground probe.
 

marvelousone

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No do not. I did not know there a such thing till tonight. I put my hand in the sump and I don't feel anything.
 
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Brew12

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No do not. I did not know there a such thing till tonight. I put my hand in the sump and I don't feel anything.
Unless you are on a concrete floor odds are you have enough insulation to prevent you from feeling a shock. To be shocked, you need a path for current to flow through you. Wood, tile, shoes, and dry carpet provide insulation that protects you by blocking current flow. The metal housing of your light fixture connects to ground. Current can flow from your tank, through you, through the light fixture, to ground.
I recommend getting something like this and plugging your aquarium equipment into it one at a time to see what trips it. Keep in mind you may need a ground probe or provide another path to ground for a GFCI to trip.
https://www.lowes.com/pd/Shock-Bust...-Single-to-Single-Yellow-GFCI-Adapter/1135923
 

marvelousone

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I have one of those gfci on my pump that I use for water changes. Thanks Yall are awesome. I will do that.
 

marvelousone

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not to highjack your thread Brew12 but this is helping me. I tested my tank today. the meter read 87.1. Turning off switches one at a time. One power head when turned off it dropped to 17.4. So bad power head. I tested the rest and it never would drop below 17.4. So do I have still some voltage in the tank. I touched the light with the volt meter and it read 17.1. I order a grounding wire. I guess I need to throw that power head away.
 

Cnidoblast

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Will plugging the ground probe into a apex controller unused outlet be okay? (I'd hope that ground is always connected regardless if the outlet control relay is on or off!!!!!!!) @Brew12
 
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Brew12

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Will plugging the ground probe into a apex controller unused outlet be okay? (I'd hope that ground is always connected regardless if the outlet control relay is on or off!!!!!!!) @Brew12
Yup, that is just fine. Until next week when you decide you need to use the switchable outlet for something! :p
 

kecked

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I had a bad shock about six months back from three faulty heaters. I removed them all and put new ones in and then found about 20v. It was the return pump. Went dc. Voltage gone. I still want to see a dc heater.

I now have a volt meter in my tank and look at it before touching the tank. I measure current and voltage.

Now I read the start of this thread about ground probes acting as heaters. Rubbish. And I’ll prove it now.

Say you have dead short 120v and a leakage current of 100ma. This is really nearly impossible. Power is voltage times current so you have 12w. Dissipation in the tank as heat isn’t a big deal. Figure the resistance of seawater and then the disapation current across that as a resistor. Just treat it as dc. Ac gets into reactance which makes this harder. So you have this current in this giant box all spread out. What you get in heat from this is going to be nothing compared to the room itself. As for the probe, the resistance is micro ohms if that. There is effectively no heat possible from the probe. I can do the math if you want.

GFI or die.
 
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I had a bad shock about six months back from three faulty heaters. I removed them all and put new ones in and then found about 20v. It was the return pump. Went dc. Voltage gone. I still want to see a dc heater.

I now have a volt meter in my tank and look at it before touching the tank. I measure current and voltage.

Now I read the start of this thread about ground probes acting as heaters. Rubbish. And I’ll prove it now.

Say you have dead short 120v and a leakage current of 100ma. This is really nearly impossible. Power is voltage times current so you have 12w. Dissipation in the tank as heat isn’t a big deal. Figure the resistance of seawater and then the disapation current across that as a resistor. Just treat it as dc. Ac gets into reactance which makes this harder. So you have this current in this giant box all spread out. What you get in heat from this is going to be nothing compared to the room itself. As for the probe, the resistance is micro ohms if that. There is effectively no heat possible from the probe. I can do the math if you want.

GFI or die.
Just want to clarify a few things for people reading this.

First, DC pumps can induce AC voltages into an aquarium. You need a True RMS voltmeter in order to read it accurately but it does happen.

It is correct that the ground probe cannot act like a heater. It can, in some very unlikely situations, allow the source of the fault to generate heat. For this to happen you would need to not be running a GFCI and have a relatively high resistance fault at the source. In theory, a fault like this could generate over 1800W of heat.

But again, this is incredibly unlikely. Most failed electrical devices in salt water will trip the circuit breaker on overcurrent if a GFCI isn't used.
 

HKfshkpr1

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OK, I am ready to install one( at least). My question is: my "system" also has a refugium and a sump all linked together, totalling about 250 gal.
Do I need 3 probes or just 1?( the heaters are in the sump but there are powerheads in the display and refugium). Thank you!
 
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Brew12

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OK, I am ready to install one( at least). My question is: my "system" also has a refugium and a sump all linked together, totalling about 250 gal.
Do I need 3 probes or just 1?( the heaters are in the sump but there are powerheads in the display and refugium). Thank you!
You should be fine with just one in the sump. The only time it won't cover all 3 is if the return pump isn't running.
 

kecked

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Put one in every box of water. You can’t have to many
 

Fliper

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Fantastic. Just knowing that one or two people are buying grounding plugs because of my post makes the time I put into this worth while!
I bought one too. Good idea. Why do many people are against them is beyond me? Anyhow, I’ve been in this hobby for 12yrs and never even heard of using one. But, I have one now. Also, I checked my stray voltage and it was 12v. It’s now 0. Thanks! I’m sure my fish are thankful too lol.
 

HKfshkpr1

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You should be fine with just one in the sump. The only time it won't cover all 3 is if the return pump isn't running.

Ok I think I'll go with only 1. In the 25 years of freshwater fish keeping I have never used one and had no problems. But now I'm keeping saltwater fish...........
Thank you!
 
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Brew12

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Ok I think I'll go with only 1. In the 25 years of freshwater fish keeping I have never used one and had no problems. But now I'm keeping saltwater fish...........
Thank you!
Yup, a ground probe is absolutely worthless in freshwater. I consider them vital in saltwater.
 

deedubz

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Not to mention a ground plug makes a GFCI much more effective. It is possible that a faulted electrical component won't trip a GFCI immediately because the insulating aquarium prevents current flow to ground. It won't trip until either you touch the water or you get enough salt creep. I don't want one GFCI tripping to take out my entire aquarium so I have decided to put each "wet" component on it's own GFCI receptacle. Hence what you see on my setup. This way one faulty heater doesn't take out my other heater, return pump, or skimmer. Each receptacle pair is fed from an Apex outlet so I still have full controllability as well as GFCI protection.
IMG_0526.JPG

Does your apex then connect to an in-wall gfci receptacle?
 
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