MH bulb life...

[r00onmac]

I know that MH bulbs can run for 20,000+ hours, but not for aquarium purposes because the spectrum changes...

i run a single 150w DE MH over my 20L and it runs between 10-12 hours a day... its been on since August of last year - so about 8 months - so approx 2640 hours on the bulb...

is it about time to change the bulb? ive been getting hair growth - which i think is a combination of a few things: Mh bulb life, overfeeding by a tank sitter, use of ~5 gallons of spring water for top off when i couldnt get RO/DI, use of supermarket brand RO because LFS RO/DI is broken...

 

[gsoaxionsk8]

I would say you probably have some time left in it. Normally you will start to get a lot of diatoms when the bulb is starting to go in my experience.

 

[dougchambers]

Mileage can vary, but most people tend to change out their MH bulbs at the 9-12 month mark. We lean towards the 9-10 month point with our 250W SE bulbs.

-Doug

 

[Sk8r]

If you want to be absolutely sure your tank doesn't suffer a 'spectrum change' issue, and cost is not an issue, change them before the statistical date.

 

[r00onmac]

lol cost is always an issue... but my reef is very important to me, so i can deal...

last time i replaced at 7 months when i started getting some hair and it cleared up right away... so i assume there was a spectrum change... and i tossed the old bulb...

maybe this time ill keep the old bulb safe in case i want to hook up a second fixture over my fuge for chaeto growth or something...

specifically speaking though, is there a general "hours of use" number that can be used to know when to expect a spectrum shift?