Originally Posted by
KENTUCKY BOY
http:///forum/post/2822802
Ok Sweet
So Whats Up With Replacing A Mh Bulb Evey Year??????????
Not all MH bulbs degrade at the same rate. Some can last 4 years, some only last 6 months.
You see, they may be still putting out light and look bright to human eyes but they may be putting out less than half of the light of a newer bulb because the phosphors wear out.
I recommend a LUX meter (because PAR meters are too expensive). A LUX meter cannot tell you how much light a bulb is producing, but it can tell you the relative health of the bulb if you record the Lumens from when the bulb was healthy.
About one month after you start using a bulb record the Lumens from about 6" away. Then periodically test the bulb from the exact same distance. I replace my bulbs after they degrade 15%, you can do more or less, it's up to you.
Just replacing bulbs every year is blindly throwing money away, or you may be starving your corals without realizing it.