How to Replace a 4 Bulb Fluorescent Light Lens

All good aquarium light fixtures have a transparent lens between the aquarium water and the light bulbs, for good reason. This simple piece of plastic protects the lights from random droplets of water that would otherwise strike the lights, potentially causing electric shorts, fires or exploding bulbs from cold water hitting hot glass. Over time, these droplets leave deposits on this lens, diminishing the light output reaching the tank and inhibiting the growth of corals and plants. Replacing the lens is a good way to maintain optimum light levels, and fabricating a new lens is relatively simple.

Things You'll Need

  • Screwdriver
  • Measuring tape
  • Saw
  • Plastic-cutting saw blade
  • Thin plexiglass sheet
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Instructions

    • 1

      Remove the current light lens from the fixture. To safely accomplish this, unplug and unmount the fixture and place it on a stable surface. Some units have screws keeping the lens in place, while other units simply have the lens mounted in slots.

    • 2

      Measure the dimensions of the current lens. Include not only the length and width, but also the thickness. This last measurement will help to make sure that the replacement lens fits properly in the lighting fixture.

    • 3

      Purchase a clear plexiglass sheet from a local hardware or home improvement store. Make sure the length and width of the sheet are at least as large as the dimensions of the old lens. Buying a larger sheet than necessary may allow for multiple lenses to be fabricated for future use. Also, ensure the plexiglass sheet is not thicker than the old lens. A thinner sheet is acceptable, because it will let more light pass through. Conversely, a thicker sheet of plexiglass may not fit into the light fixture and will reduce light output.

    • 4

      Mark the dimensions of the old lens on the new plexiglass sheet. A pen is the simplest marking method, although putting down brown masking tape to outline the new lens may make visualizing while cutting easier.

    • 5

      Cut the plexiglass using a saw and a saw blade designed to cut plastic. Many types of saws, such as jigsaws, band saws, scroll saws and table saws can cut plexiglass successfully. Work on a steady surface, like a workbench, for safety and control. Be sure to let the saw's speed spool up before attempting to cut the plexiglass. Store any unused plexiglass for future use.

    • 6

      Install the new lens in the light fixture and remount the fixture over the aquarium.