Thursday, September 18, 2008

Coralife Aquarium Lighting

A few years ago I bought my wife a Coralife light fixture for her salt water aquarium. It’s a four-bulb fixture, intended for a pair of Actinic lights, and a pair of daylight balanced (she runs 10k’s). The first year or two, it ran fine, although she never replaced the bulbs.

About two years ago, we started having problems with the lights not coming on, and from the looks of these four-conductor plugs, I assumed that it was corrosion. It took a while, but I was finally able to pry the bulb off of the connector with a blade screw driver, but in the process, I destroyed one or two bulbs. The pins from the bulb were so corroded that they broke right off. This obviously was no good.

I did some asking around, but didn’t really like any of the answers I got, so after re-investing in a new set of bulbs, I set out to try to stop this corrosion.

What I decided to try was some Silicone Grease that I purchased at the automotive store. They call it Spark Plug Grease or Dielectric Grease. About a year ago I replaced two of the four bulbs. After removing the old ones, I cleaned up the plug with an acid brush (although a pipe cleaner would have worked better I think). I squeazed some grease into the plug, and put a good healthy lather on the pins coming out of the bulb.

When I plugged the bulb in, I was careful to make sure that the plug was on as far as I could get it. Not only that, I also made sure that the metal contacts were not exposed to the (salty) air, but were instead all gooped up in grease.

So now, a year later, how has it gone? Well, overall pretty good. This time when I went to change the bulbs, I had very little problem disconnecting the pair that had been cleaned and greased. The un-greased pair was more difficult to remove. Also, you can sort of see in the photo below the difference between a bulb that had grease applied (top) versus one that didn’t have any grease. It’s hard to see, but the top one is more yellow or brassy colored. The bottom one is more reddish-orange from the corrosion.

The only bad news is that on one of the plugs that was greased, it appears that the plug got very hot and actually melted the side of the plug away. At this point, I don’t believe that it was directly related to the grease, although I’m not ruling out the possibility yet. Of the eight pins that were greased (four pins times two bulbs), only one pair had this heat damage. The other six were in good condition.

Below is a photo of the newly greased plug on the right, and on the left is the bulb with a bad plug. The green you see is the bare copper wire that had corroded. This plug will have to be replaced.

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