when change MH bulb

[baruchbl]

How long can i run MH bulb?

[prodman]

what kind of bulb is it?

[Bruddah Chrispy]

I think the general rule of thumb is 1 year, but it is obviously going to vary depending on your lighting schedule, your ballast, your bulbs et al. You could get a light meter and monitor the output.

I just change mine every year.

[baruchbl]

I use Iwassaki bulb.
Can you give me an explanation for which bulb how much time it can run?
And how much important is the ballast? is it change the answer and how much?

[graff71884]

Iwasaki is a good brand of bulb, so they would probably stay in spectrum longer than some others. Depending on how long you run the bulb per day would also depend on when to change it because running the bulb longer each day would cause the spectrum to run out sooner. Magnetic ballast will wear a bulb out faster than electronic ones faster as well.

[Steve Ruddy]

You could get a light meter and monitor the output.

Short of that you will be able to tell by looking at your corals. Some of them will start to look darker.

[yaktop]

9 months is the outside edge for me. I will start to notice algae at that point.

[Steve Ruddy]

After some more thought. Even with a light meter we should still know what corals are being kept before we can give a bulb life expectancy statistic. It's been my experience that certian corals will tolerate older bulbs while others will not. With this in mind it maybe only possible to get a general bulb life expectancy if we can compare the following:

Aquarium dimensions
Aquarium material/open top
reflector type
bulb manufacturer
kelvin
wattage
ballast
photo period
other light supplememtation
type of corals being housed

I'm sure ther are also other things I haven't listed.

All this aside I usually give the following recomendation.

6500k 1-2 years
10000K 9-12 months
20000k 6-10 months

[yaktop]

Originally posted by Steve Ruddy
After some more thought. Even with a light meter we should still know what corals are being kept before we can give a bulb life expectancy statistic. It's been my experience that certian corals will tolerate older bulbs while others will not. With this in mind it maybe only possible to get a general bulb life expectancy if we can compare the following:

Aquarium dimensions
Aquarium material/open top
reflector type
bulb manufacturer
kelvin
wattage
ballast
photo period
other light supplememtation
type of corals being housed

I'm sure ther are also other things I haven't listed.

All this aside I usually give the following recomendation.

6500k 1-2 years
10000K 9-12 months
20000k 6-10 months

i can agree with that assuming the 6500 are for the refugium in their later months. I used 6500k's and started to notice algar growing after the first year. great for macro though.

[AquamanMax]

What is it about an older bulb that causes algae? Decreased intensity or change in spectrum?
People use different wattage and different "K" rated bulbs all the time.

[graff71884]

It is change in spectrum. They shift into a spectrum that is not suitable for reef aquaria and it causes algae growth.

[km133688]

This is something that confuses me:

If a 20000k bulb looses say 50% spectrum, is it not now operating like a 10000k bulb? So if I am using 10000k bulbs in my tank, why don't I just start with a 20000k bulb for the same prices and waite twice as long to replace them?

Somebody straighten me out here.

[Bruddah Chrispy]

The spectrum is not the same as the Kelvin rating. The K rating is the perceived 'whiteness' of the light compared to a known standard. The spectrum is the wavelength(s) at which the bulb radiates.

[km133688]

Yeah OK, that I can understand.

So what drops, Kelvin, Spectrum, both I asuume. And won't a 20000k blub after dropping 50% work like a 10000k bulb?

Can the spectrums for a 10000k blub and a 20000k bulb be the same?