How often to change lights?

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Aquarium Advice FINatic
Apr 20, 2008
Findlay, Ohio
Just curious since i've heard a few things.. how often do you have to change PC bulbs? I've heard anywhere from 6 months - 1 year to well up to 2 years. I've had mine for about 8 months ( got them used with two months on them before) for about 8-9 hours a day. Should I change them or wait a bit longer?
Here is just some simple numbers that Liveaquaria gives. I know the number of months will vary depending on hours used and system used. But it gives you a round number to look at. I use VHO`s and I was thinking the numbers they gave was a big difference.

"How often should I replace the bulbs and why?
The intensity of a bulb diminishes over time. Even though the bulb will still light up, it may not be emitting the necessary spectrum or intensity to support healthy growth. In many instances, the diminished light output can encourage nuisance algae growth.

Incandescent Bulbs - Replace every 2 to 4 months.
Standard Fluorescent Bulbs - Replace every 6 to 18 months depending on ballast type.
VHO Fluorescent Bulbs - Replace every 4 to 18 months depending on ballast type.
T-5 HO Fluorescent Bulbs - Replace every 16 to 24 months.
Compact Fluorescent Bulbs - Replace every 14 to 24 months.
Metal Halide Bulbs - Replace every 6 to 18 months".
I run a 10 hr cycle on the 10k lights, and a 11.5 hr cycle on the actinics. I change every 6 months, like clockwork. And I am always amazed at how much brighter the lights are after I change them!
I change mine every 6 months too Kurt but I was surprised that the good doctors would suggest as much as 18 months. I`m sure some of that is salesmanship.
12 to 24 months? Wow.. big difference from that and from what Kurt said. Have anyone whos gone longer than a year seen any difference ( good or bad?)
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