Should you use a grounding probe in your aquarium?

We get asked that from time to time and our advice is that you should use both a GFCI and a grounding probe. 

With all the equipment we use in our aquariums there is always the possibility that some type of short or ground fault will occur. A "ground fault" is a conducting connection between any electric conductor and any conducting material that is grounded or that may become grounded. Electricity always wants to find a path to ground. In a ground fault, electricity has found a path to ground, but it is a path the electricity was never intended to be on, such as through a person's body.

Fortunately there is a device called a GFCI (Ground Fault Circuit Interrupter) that will "sense" the difference in the amount of electricity flowing into the circuit from that flowing out, even with a variation in the current as small as 4 or 5 milli-amps. As soon as the GFCI senses that variation it trips the circuit (in less than one-tenth of a second) and cuts off the electricity. GFCIs can save your life and in our opinion should always used around water.  In fact it might even be a legal requirement depending on where you live.

By this point you might be saying...okay I get that, but what does this have to do with whether I should use a grounding probe or not?

As mentioned, in order for the GFCI to trip it needs to sense the variation in current and that is where your grounding probe comes into play.  When you use a grounding probe along with a GFCI, it will cause the GFCI to trip when the short occurs (assuming it is great enough). That will protect us humans as well as our live stock since the GFCI will shut the system down. It is true that the power outage that is created can cause other issues but it is probably a case of better safe then sorry. If for some reason the GFCI isn't working, your live stock may suffer and as tough as that might be, it should serve to alert you to the problem before you put your hands in the water and find out about it the hard way.

On the other hand (no pun intended) if you don`t use a grounding probe, your GFCI won`t trip until a ground is provided and this will usually happen as soon as you put your hands in the tank. Hopefully your GFCI is working at that point.  Until a ground is provided the current is still flowing but your live stock should be okay since there is no ground.  For these reasons it is our opinion that you should always use both a GFCI and grounding probe together.  You should also ensure that your grounding probe is plugged into the same circuit as your GFCI.  If it isn't your GFCI won't sense the difference in current and protect you as intended.   Be safe...make sure you run both a GFCI and grounding probe on your aquariums.