My son was playing around with my electric sinsitivity tool. It lights up when it senses electricity in a wire. It was lighting up when placed against the glass on one of my tanks. This tank has two filters and when I unplugged the Aqua-Tech 5-15 the lite went out. The fish seem fine. The filter has one of those removable magnet drive motors with an o-ring seal.
This is freshwater. Years ago I had a saltwater tank with a tingle when you touched the water. The salter corrosion had gotten to the old style heater. I have no tingle in this tank.

One doesn't see problems with stray voltage in FW tanks, at least AFIK. I guess it would depend on conductivity (hardness). It IS curious that your meter detected voltage from your filter, given that the motor is electrically isolated from the water. Induction perhaps? I wonder how that would work...

I guess I should ask if this instrument detects current, or potential (i.e. voltage), or what?? Not that I'm any kind of expert.

My Harbor Freight Link

Heres a link to the tool. It sences electricity on the outside of a wire and in or near an outlet. I checked again. It activates on the glass and in the water. It does nothing on my other tanks.

Edited by njJohn, 27 November 2010 - 01:04 AM.

I would inspect all of your mechanics, just in case. If it's a small problem it could get larger.

Well you could do what the reefkeepers do. Add a grounding probe. I don't understand how this could happen with a magnetically coupled impellor, but there you go. I have a similar problem with one of my guitars - getting noise (i.e. ground hum) from the pickup. Running it down is an exercise in frustration.

I had a submersible pump that was leaking enough voltage that if I was barefoot on the concrete floor and stuck my hand in the tank, that I would get a slight shock. The first time I dismissed it, thought I was mistaken, until I stuck my hand in the water at a later date, while having a small cut on my finger. I used myself as the tester, and unplugged various things until I isolated the pump. Never seemed to bother the fish, but I got rid of it for fear that the stray voltage would worsen, and become dangerous. Danner mag drive pump BTW.

Most of my stuff is old and/or used.
I got used to testing the water by just sticking a right hand finger in my saltwater tanks, while standing on my right foot [keeps the jolt away from the heart]. Have even gotten tingles from touching the salt crust on the outside of the glass.
never knew it to harm the fish.

I added grounding probes to most of my tanks a while back. The stray voltage in some of them seemed high, especially in the brackish tanks. I was having some problems at the time, but it turned out that they weren't voltage related.

As far as I understand, those tools work via inductance - the flow of electrons in a nearby material causes electrons to move in the instrument. My hunch is that your instrument is just hitting on the functioning electronics, not electrical current at large in the tank. You should be able to measure current in the water with a multimeter to see if there is really a problem.

I tried a multimeter last night and got no readings. I'll get a new filter when the funds allow. Maybe I'll ask for a petstore gift card for Christmas.

I added grounding probes to most of my tanks a while back. The stray voltage in some of them seemed high, especially in the brackish tanks. I was having some problems at the time, but it turned out that they weren't voltage related.

I did this in one of my tanks too though it was freshwater. It was getting stray voltage from a flourescent light that seemed to be causing problems for a bullhead. I found the voltage with a multimeter though, and it is no longer detectable with the grounding probe in place.

Most of my stuff is old and/or used.
I got used to testing the water by just sticking a right hand finger in my saltwater tanks, while standing on my right foot [keeps the jolt away from the heart]. Have even gotten tingles from touching the salt crust on the outside of the glass.
never knew it to harm the fish.

I'm pretty sure my issues were with submerged powerheads and I only seem to detect the tingle [sometimes more than tingle] in salt water.
I've gotten more serious jolts from leaky or cracked heaters.
The powerheads seem to work fine and last along time, even when tingly. Obviously leaky heaters get chitcanned.

Chronic exposure to low voltage may not cause obvious fish health problems, but I wouldn't rule out the possibility of gradual damage to nerves, lateral line organs, and immune system suppression. Sounds like torture to Gymnotids and Mormyrids that rely on electrical field navigation.

never knew it to harm the fish.

FishHead: If this tool works by inductance, how can it measure voltage in a wall socket that nothing is plugged into?
No current = no inductance, right? or am I missing something?

On a vaguely related subject, I have a IQ Scientific ISFET pH meter that gave vastly different readings when used in the fishtank vs used in a cup of water taken out of the tank. At first this made no sense, then I figured out that maybe electrical or magnetic fields from the lights, pumps etc could be skewing it when used in the tank. So now I only use it in a cup, away from anything electric. (An ISFET pH meter does not use a membrane like standard pH meters, but it's supposed to work better in very low conductivity water where membrane-type pH meters have trouble).

Hmmm... if only we had a chemical engineeering major to explain this better ...

Hmmm... if only we had a chemical engineeering major to explain this better ...

Don't look at me. Well, I guess I could send the link to this topic to a professor and see what they have to say. *sends*

Edit: Update: I have e-mailed the question and a link to this discussion to the Circuits teacher at CWRU.

Edited by EricaWieser, 02 December 2010 - 05:18 PM.

Dr. Merat, the current teacher of ENGR 210 (Circuits) at Case Western Reserve University, said the following:

I am not sure about the instrument being pressed up to the glass of an aquarium or the rest of this information.

However, a wall socket is always live unless switched off at a supply point such as a breaker panel or properly wired switch. You should not have any outlet or any live electrical device in the water unless proper precautions are taken to isolate it from the water. And electrical outlets near water are required to have GFCI (ground fault circuit interrupters) which will detect any imbalance between the hot and neutral (for example current going where it shouldn't such as a human body) and very quickly break the current flow. You probably don't need to have a GFCI outlet near an ordinary hobbyist fish tank but serious fish operations with any plumbing such as a water pipe or a drain pipe would require one.

Yes, water typically conducts electricity and if you are measuring a voltage on the outside of a glass tank there is a problem. As the impurity content of water increases (especially impurities such as salt) the conductivity increases and current flows. On the other hand if you are using an electric field sensor (these are wonderful gadgets often called tic tracers which use capacitive sensing and electric field coupling) to determine if something is electrically live without the necessity of a current flowing. This means that there is a voltage on the wire and, if you would touch it, that touch could result in an electrical shock whose magnitude would depend upon a number of factors such as the voltage present, skin conductivity, what part of the body was touched, and what ever else that person was touching. Touching a 120 volt wire while also touching a cold water pipe or other grounded surface could result in electrocution and death. However, an electric field sensor simply indicates the presence of an energized wire and does not indicate that current is actually flowing through anything -- that must be checked with a regular ammeter.

If you watch Myth Busters they explored the James Bond premise that someone in a bathtub could be killed by dropping a plugged in toaster into the bath water. The GFCI was extremely effective in their demonstrations.

Hope this helps.

Dr. M.

Edited by EricaWieser, 03 December 2010 - 09:32 AM.

Oh, and this might be helpful. I found out that the Aquatech 5-15 gallon filter has a manufacturer's warranty of 2 years. Info: http://www.walmart.c...tem_id=10313136

Quote: "Supplier Warranty: Within two years from the date of original purchase, your Aquatech Power filter will be reparied or replaced (manufacturer's option) for any defect deemed to be due to workmanship or materials. Damages or injuries resulting form neglegence or misuse are not covered under this warranty. This warranty gives you specific legal rights. Incidental or consequential damages are specifically excluded unless you state prohibits such exclusions. You may also have other rights which vary from state to state. Please call 800-322-1266 for further warranty information and return address."

Edited by EricaWieser, 03 December 2010 - 09:38 AM.

Thanks, I had the feeling this was a made for Wal-Mart only filter.

Since the motor is removable and there is a o-ring seal to prevent water from leaking out of the tank. There must be a small seal to prevent water fron leaking into the motor. Maybe thats whats going on.