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Aquarium.Net Stray Voltage

This month Bruce discuss voltage in the aquarium and answers readers questions, Sept. 1996 Aquarium Net, Aquarium Net has numerous articles written by the leading authors for the advanced aquarist

Stray voltage in the aquarium

How does it get there and what effect does it have on our animals.

By Bruce Davidson

Voltage can enter our aquariums by several means, one of the most common is induction. Induction is the process by which an electric current, an electric charge, or a magnetism is produced by the proximity of an electric or magnetic field. Let's see; do we use any magnetic fields or electric charges in the proximity of our aquariums? You bet we do. Power heads and large water pumps have both. Fluorescent lights have a strong electric charge in that tube. As air bubbles burst at the surface of the water they spray salt several inches. Salt creep or salt spray can form and give electricity a path from lighting, heaters and powerfilters to find the aquarium water. Because of the conductive properties of salt water all equipment (heaters, lights, powerfilters etc.) should be kept clean of salt spray and salt creep. Non submersible heaters should never be used on a marine aquarium. Not only because of the potential of stray voltage in the aquarium but they will eventually stick in the on position.

Now we know were it comes from so how do we test for it? Using a voltage tester or volt meter set to read AC voltage (VAC) put one lead on a known ground and the other in the tank water.

The first tank I tested was my 125 gallon reef tank. The tank is acrylic and sits on a wood stand. All lighting is suspended ten inches above the tank. I use an Iwaki pump for water return and three Maxi Jet power heads in the tank for circulation. I have a 300 watt submersible heater in the sump. After finding a good ground I set the volt meter to VAC and to my surprise I had 12.5 volts. Intrigued by the amount of voltage in my tank at home I thought it would be a good idea to check all of my marine tanks at work. I found every marine tank has some detectable stray voltage, from .63 VAC on a twenty gallon tank to 43.62 VAC on a 110 gallon wall unit. Even at nearly 44 VAC we did not feel any shock when we put our hand in the water, I wouldn't try it barefoot.

Next step was to eliminate the stray voltage. On every tank I unplugged each piece of electrical equipment one at a time wile testing for voltage. On most tanks it was a combination of every appliance leaking or inducing voltage but in some cases I did find faulty powerheads and even a few faulty submersible heaters. Once faulty equipment was ruled out or replaced I needed to ground every tank's water. At the time of my testing commercial ground probes were not available. I used a length of stainless steel wire, one end connected to an electrical ground and the other placed in the aquarium water. Since the current travels through the entire system there is no need to put the ground in the tank. I prefer the ground probe to be in the filter or sump. Several companies have since come out with ground probes. The most popular design is a titanium probe that will be in contact with the water. Copper wire runs from the probe to a spade connector that you attach to an electrical ground.

If it does not shock us, why do we care if we have voltage in our aquariums?

Fish have a sensory organ called the lateral line complex. With this organ the fish can detect pressure changes in the immediate vicinity, from the movement of currents or from other fish. It is also used for navigation, finding food and avoiding predators. In most fish this lateral line complex can also detect or sense electrical charges in the water. If you have any stray voltage in the water it can overwhelm this organ, much like living in a deafening noise environment. This will cause stress, and among other things, suppress the immune system making your fish more venerable to natural bacteria and parasites which occur in every tank.

On my first test tank, my reef, I had a yellow tang that I would say was skittish at best. You could only observe this fish if he did not see you. Immediately after grounding this aquarium the yellow tang would swim in front of anyone without fear.

Stray voltage has been speculated to be one of the factors that can cause Hole in the Head and Lateral Line Erosion (HHLLE).

Stray voltage is something that exists in every tank. Stray voltage can be eliminated with a simple ground probe available at most pet shops in the twenty dollar range. Elimination of stray voltage is a simple step in reducing the stress on your fish. Every marine tank should be grounded for you and your fish's protection.

Bruce ,

What with all the lighting equipment and specific spectra needed for growing corals and all, I ask if these lighting systems are also required by fish. I mean, they don't have those photosynthetic zooxanthellae and all that, so what would be enough?

Specifically, for a 150 gallon tank (2 ft x 2 ft x 5 ft), would normal output (40 watt) bulbs be sufficient? I was planning on four (2 Actinic 2 Daylight). Is this good enough? What other suggestions do you have (example 1 Actinic, 1 50-50, 2 Daylight or whatever combination you think is nice).

Thanks for any info!

--Alf R. Racho

Manila, Philippines

Alf ,

The main thing is for you to select a light package that YOU like. By that I mean one that makes the fish and the aquarium look most natural. Because the tank is fairly deep I think four standard watt (40w) florescent tubes will be best. My personal preference is an equal mix of actinic and full spectrum/daylight. Fish or any animals do have some pretty specific lighting requirements but they mostly pertain to photoperiod or duration that the lights are on. Most if not all animals have different daytime and nighttime activities. There is a gland in the brain called the pineal gland. This gland takes sensory input from the eyes and visual cortex of the brain that monitors the length and regularity of the photoperiod (day verses night). The pineal gland uses this input to produce hormones and secrete them into the blood stream. These hormones help the animal effectively carry out it's daily functions. This is kinda like the biological clock keeping track or the days and seasons for the animal.

Daily functions regulated at least in part by this include feeding, seeking out shelter, hiding from predators and changes in pigmentation. Seasonal changes in hormonal output regulate mating migration and hibernation. Changes in light duration or photoperiod causes the pineal gland to secrete these hormones very erratically which upsets the balance of all of the body's systems. This can suppress the immune system which among other things and cause your fish to be more likely to get parasitic or other infections. What ever lighting you go with you should use a timer and set a cycle that allows maximum viewing time for you and stability for the fish.

ttys Bruce ~Philoicthyoecetes~


I am setting up a 45 gal (mainly fish) marine aquarium. I am about 28 days into the cycle. Ammonia is at zero, Nitrite is dropping, but I have not seen Nitrate skyrocket yet. Have done no water changes yet. My main question is should I be running my skimmer during the cycle? I did not have it on at the start, but now have been running skimmer for about a week. I've gotten about 15cc of a thin light brown skimmate.

Thanks, Ronald T. Gerken

Ron ,

Running the skimmer or not during the cycle depends on a few things. If you have live rock in the system, my preference, you should run the skimmer as soon as the live rock is introduced. This can be done the day after the tank is set up if the salinity and temperature are right.

If you are starting a fish only system with a biological filter and no live rock I recommend NOT running the skimmer for the first two weeks. I have found that if you start the tank with an efficient foam skimmer it will prolong the cycle. Give the tank a couple of weeks to produce ammonia and nitrite this will give plenty of food to the bacteria that we are waiting to develop. Once the bacteria have colonized the bio media crank up the skimmer.

Now would be a good time to do a water change. I suggest up to a twenty gallon change for your 45 gallon tank. I do not think it is a good idea to clean anything at this point, just water out and water in.

ttys Bruce Davidson º Philoicthyoecetes º

Created by liquid
Last modified 2006-11-19 01:38