Multimeter

[-Logzor]

What kind of multimeter do I need to measure voltage in my aquarium? I wasn't sure if there is a specific kind or maybe something cheaper than i can use?

 

[steamer51]

The cheap meter I bought at Harbor Freight is fine, you don't need anything fancy. Put the positive (red) probe in the water and touch the black (negative) to a ground. My tanks are in the unfinished part of the basement so I just touch the probe to the concrete floor. If I find a couple of watts leaking (stray voltage) I start unplugging powerheads, heaters etc. one at a time until it goes to zero to identify what is causing the problem.

 

[redfishbluefish]

Agree that the inexpensive meter from Harbor Freight being just fine. With the meter set to AC volts, it doesn't matter which color probe you put in the water. I would also find a better ground. I use the screw on the coverplate of an outlet. A few volts are just fine.

 

[-Logzor]

Thanks for this information, I thought you put both probes in the water (shows how much I know on the topic...)!

Now my basement is carpeted and I'm not sure how long the cords for the probes are, so I may not be able to reach an outlet. What should I ground to? Is there anything mobile I can use?

I ended up getting one for $20 on amazon, free shipping (prime).

 

[redfishbluefish]

Now my basement is carpeted and I'm not sure how long the cords for the probes are, so I may not be able to reach an outlet. What should I ground to? Is there anything mobile I can use?

Assuming you have grounded outlets....three prong....house built within the last 50 years.....use an extension cord and use the ground prong hole as your ground.

 

[-Logzor]

I have a ground checker, only about half of the outlets in my house are grounded, built 1949. I'll definitely try this.

 

[Akira]

You can also put the end out of water to the neutral on any recepticle. Hot side of the plug is always the small slit neutral is the longer slit. That is assuming it is wired correctly. You can get a checker that looks like a cord end that you ust plug into an outlet that will tell if its wired correctly and if it has a ground. Make sure to get the 1 that has a button on it and it can also make a GFCI trip to check them too. Should be about $8 at horrible freight.

 

[-Logzor]

Which selection on the multimeter do I use on the aquarium and what do I look for, what is normal?

 

[-Logzor]

Ok using the 200 ac voltage setting I hit 26 with everything on, each piece if equipment is leaking a few volts each. I'm not getting shocked so there is no current, just voltage. Should I take any action?

 

[MBSL55]

Tagging along to see what others say. I get a fraction of a volt when I test mine (0.141 VAC as tested with a Fluke DMM) so 26 sounds too high to me.

 

[MBG75]

It should read 0.

What are you touching the probe to as a ground?

Your not getting shocked because your not touching anything that's grounded.
Have you shut one item at a time till it drops to 0?

All tanks should run a grounding probe.

 

[-Logzor]

Im touching to the ground on an outlet. I think you might be confused there is a difference between leaking current and leaking voltage.

 

[redfishbluefish]

26 volts….you’ve got a problem. Start unplugging until it drops down to a volt of two.

It should read 0.

I’ve never seen a tank at zero. You’re OK up to a few volts.

All tanks should run a grounding probe.

I respectfully disagree with this. A grounding probe only protects you when you put your hands in the tank. I would rather feel that tingle in my hands to know that I’ve got a voltage leak. Further discussing the probe, it now creates current. Without the probe, there is the presence of voltage but no current. Think of a battery sitting on a shelf….there is voltage but no current. The probe provides the path for there now be current flow. And current is the problem.

 

[MBG75]

26 volts….you’ve got a problem. Start unplugging until it drops down to a volt of two.




I’ve never seen a tank at zero. You’re OK up to a few volts.





I respectfully disagree with this. A grounding probe only protects you when you put your hands in the tank. I would rather feel that tingle in my hands to know that I’ve got a voltage leak. Further discussing the probe, it now creates current. Without the probe, there is the presence of voltage but no current. Think of a battery sitting on a shelf….there is voltage but no current. The probe provides the path for there now be current flow. And current is the problem.

Logzor, I'm not confused.



The voltage reading he is getting is called potential. Even though there is no current, the electrical energy is still in the tank. My tank tests at 0 with a Fluke 334.
Feeling the tingle in your hands has the potential to hurt or kill you. You don't know the current that can be behind that voltage reading. Could be 0 amps or a lot more. Only need 1/4 amp to stop your heart.
There are reasons why GFCI are required in wet locations, and as far as a tank is concerned, a GFCI is useless without a path to ground (grounding probe).
Sorry if it sounds like I'm venting, but I don't want to see someone hurt.

 

[-Logzor]

Well the problem is each piece leaks a little bit. I hear this is very common even with new equipment.

 

[-Logzor]

Also the water is not shocking me. Isn't this the same concept as birds on high voltage wires? How does just leaky voltage harm my corals?

 

[Young Frankenstein]

Multimeter's are fairly cheap now a days and accurate. You will be needing a mv range milli volts, the voltage you will be measuring will start at the 200 v range and downscale to mv, more than likely if you have power heads you will be measuring stray voltage in the 800mv to 1.5v range. To measure one end needs to go to the ground side of a receptacle or any ground available from a metal fixture etc, and the other side to the tank. Hope this helps If you do want to eliminate stray voltage you will need a GFI and a grounding probe. Do not install a grounding probe without a GFI protecting the power head, reason for that is without grounding anything there is no way out for voltage to ground, therefore you can have 120v in the water without problems, considering there is no ground.

 

[redfishbluefish]

Also the water is not shocking me. Isn't this the same concept as birds on high voltage wires? How does just leaky voltage harm my corals?

You are correct….you are a bird on a wire. You are not grounded. You are not creating current. If the VOM says that you have 26 volts, you do have a voltage leak problem. Again, using the VOM (multimeter), start unplugging until you identify the problem equipment and replace it.

MBG unplug your probe and test your voltage….I guarantee it’s not zero.

 

[-Logzor]

I tried this and every pump leaks 1 or 2 volts.

 

[-Logzor]

Bottom line, if I do not have gfci should I or should I not run a ground probe?