You can feel it – it’s electric! Boogie-woogie-woogie.

Tonight I was working on my fishtank. I’d recently rearranged some corals to let them get a little more light and also free up some new space for some new ones. The side effect was that I’d noticed that one coral was stinging another one (too close together) and had decided to move them apart. While I had my hand in the tank, I noticed a pins-and-needles feeling in my arm that was underwater and moving the coral.

Hm, I thought – pinched nerve? Was the coral stinging me in some new and unusual fashion? I dropped the coral on to a rock and pulled my hand out, then squeezed my arm with the other hand. Nope, nothing felt unusual. I put my hand back in the water and immediately felt the sensation again. “Let’s see” I thought. “This is a familiar feeling. I’ve felt this before – oh yea, that’s what it feels like when I accidently grab a live wire. It appears my tank is trying to electrocute me”.

I walked around the tank a couple times and looked at the many types of electrical things I have plugged in. There were five different pumps, two heaters, a chiller, a motorized turning fan, a UV sterilizer, three sets of lights, a computer and it’s many sensors, a de-humidifier, moon lights (little blue led’s), and the hood mounted fans. Nothing was obviously smoking or had warm electrical cables. I don’t remember what the logic was, but I put my hand in the sump tank in the back room and received a shock about twice as powerful as from the main tank. At this point, I decided I wouldn’t put my hand in the sump until I had better resolved the issue.

Front of the tank (it’s a little dirty right now)

Back of the tank

I realize it may at first glance appear that anybody with that number of electric cables around salt water is just looking for a complicated and expensive method of suicide, but there’s actually some safety rules and cautionary measure that I take. First, everything is plugged into GFIs. Those breakers are supposed to automatically trip if they come into contact with a ground. Secondly, all plugs and connectors are above the level of the water – so a water leak/drip won’t flow into a socket. Third – everything that’s electrical and has to sit on the floor (the metal halide lighting balasts and chiller) are actually sitting on top of something so that if there is a flood – it’d have to cover the floor by at least six inches before it comes into contact with anything electronic.

So far, following these rules has prevented me from burning the house down.

In any case, I’d read about problems with the powerhead (pumps) shorting out and electrifying the water – so those were my first suspects. So to start, I turned off everything except for the main lights and fans. I believe I have a volt-meter someplace, but I have no idea where it is and I’m not sure which setting you put it at to test for AC in salt water. So, I used myself as the meter and dipped about the first digit of the middle finger into the main tank. No shock.

I tried it a couple times to make sure, then decided I’d consider that a worthy test (still reluctant to try that in the sump). Next I turned on the powerheads in the main tank and tried it again. Again, no shock.

Now, I’ve had most of my pumps for years and years without any problems at all. The only recent addition was a dinky little one that I was using to circulate water in and out of the UV Sterilizer and chiller. It’d been in place since Christmas. That was my prime suspect at this point. I went around and in steps connected everything but that pump and tested the water without getting a shock. At this point, I was certain that was the issue and traded it out for one of the other pumps that I had laying around.

Now this pump was a smaller one then I’d normally use, because for both UV Sterilizers and Chillers, there’s a maximum flow speed for the water. You actually want the water to move slowly through the UV system so it gets dosed with light, and you want it to move slowly through the chiller so it has time to cool down. So when I changed pumps, I doubled or tripled the speed and pressure of the water running through that series of pipes. A side result of that increase in pressure or maybe just all the flexing going on with the pump change was that I saw a little leak of water coming out of one of the connectors on the UV filter. So, I reached up and and started screwing the pipe a little tighter when ZAP. Worst shock yet.

UV Sterilizers will have special names in my presence from now on.

At this point, I realized that’s what the real problem was. When I just had the pump unplugged, the water was drained out of the UV sterilizer and it wasn’t conducting to the tank. Once I restored the flow, it was free to charge back up and resume it’s attack.

So, I unplugged it, removed it from the loop, reinstalled the original pump, and turned everything back on – and it was all good.

I took the plastic case off the UV unit and it’s pretty easy to see what the problem is.

That glass container holds the UV bulb and is supposed to allow the light out while maintaining a dry interior. As we can see, there’s a considerable amount of water inside as well as some interesting scorch marks at the base.

I don’t believe I’ll be reinstalling this unit. I’ll probably also send a polite letter to the manufacture and finally – begin to do more research on grounding probes for fishtanks. In theory, one of those would have made the breaker reset before I shocked myself and I could have just gone around one-at-a-time unplugging things to see which it was.

Also, I know that PH probes work on a combination of resistance and temperature. It seems pretty conceivable that sudden stray high voltage could cause meters to give strange readings or even burn out the probe. Maybe I was unfairly blaming the drdaq folks for having poor equipment.

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