[RobG]

I installed my MH setup (2 x 250 W AB 10K bulbs on a PFO ballast) in October of last year, so it's time to replace the bulbs. I decided to try the 10K Ushio's instead of the ABs this time around and have a couple of questions:

1) Am I going to need to do any kind of acclimation switching between the ABs and Ushios or can I just keep with my 9 hour MH photoperiod?

2) How often do you need to replace VHO Actinics? I have dual 110W URI bulbs that have been there since October also...

thanks in advance for the info...

Rob

[Ninong]

Originally posted by RobG

I installed my MH setup (2 x 250 W AB 10K bulbs on a PFO ballast) in October of last year, so it's time to replace the bulbs. I decided to try the 10K Ushio's instead of the ABs this time around and have a couple of questions:

1) Am I going to need to do any kind of acclimation switching between the ABs and Ushios or can I just keep with my 9 hour MH photoperiod?

Not between the two different brands, AB and Ushio, but you might want to consider that new 250w 10,000K DE lamps of either brand will be 20% or so more intense than the 10-month-old lamps they are replacing. You could either reduce the photoperiod temporarily and/or adjust the height of the fixture, if that is possible. BTW, with your 9-hr photoperiod you should be able to go 12 - 13 months on those lamps. If you were running them 12 hrs per day you might consider replacing every 10 months. Of course, it certainly doesn't hurt to replace them every 10 months, but I think you could go longer if you want to.

2) How often do you need to replace VHO Actinics? I have dual 110W URI bulbs that have been there since October also...

Depends on the ballast. With just an ordinary ballast you probably want to replace them every 6 months. With an Ice-Cap electronic ballast you can go 10 - 12 months easily with the Actinic VHOs and longer with the others.

[RobG]

Thanks for the info... Maybe I'll wait a while before putting the new MH bulbs in.

I'm running the LampsNow electronic ballast for the VHO Actinics.

I think I'll wait another month or two and replace all bulbs at once.

[bartstar]

I'm new to this hobby but not new to lighting.

Before replacing an expensive metal halide or fluorescent lamp, check the rated life for that lamp (Philips, GE, Osram-Sylvania all have on-line catelogs). 250-watt metal halides typically have a 10,000 rated life (3 hours on, 3 hours off). However, they do have a 30-40% lamp lumen depreciation. VHO fluorescent lamps are also rated at 10,000 hours. If you're runnning the lamps 10-hours/day, that's only 3650 hours per year.

Next generation T8 and T5 HO lamps have much longer lamp life (18-24,000 hours, low lamp lumen depreciation (less than 10%), and use electronic ballasts (run cool and are quiet). Unfortunately, there is not much choice in kelvin temperatures yet.

Hope that help.

Bartstar

[Ninong]

Hi Bartstar, welcome to Reefland!

Life would be a lot simpler and much cheaper if we could base our lamp replacement schedule on the manufacturer's ratings. But we can't. Those ratings are based simply on total lumen depreciation and lamps do not degrade evenly across the entire spectrum of photosynthetically active radiation. Generally, the shorter wavelengths (violet/blue) degrade faster than the rest, causing a shift to red as the lamp ages. This condition is unacceptable in reeftanks.

So we can either replace our lamps after they lose about 25% to 30% of their total intensity or we can replace them after they have lost 25% to 30% of their violet/blue wavelengths. We cannot let them go 40% because that would be harmful to the animals in the tank, too much reacclimation stress. To complicate matters, not all metal halide lamps deteriorate in the same manner. The 400w 20,000K Radiums, for example, lose almost 40% of their violet/blue range within the first 6 - 9 months, when running them 10-12 hrs/day. So, even if they have lost only 20% of their total intensity, we have to replace them because they have shifted too much.

The 6500K Iwasakis can probably be run the longest. They are usually good for about 18 months running 10-12 hrs/day. Most of the others should be replaced after about 12 months, unless you are running them less than 10 hrs/day. The 150w 10,000K DE lamps seem to last about 16-18 mos. with no problems.

So it's really not as simple as checking out the manufacturer's rated life.

[mrok12]

I agree with you Ninong. I run 20K bulbs 10 hours a dasy ( 400 ) and have resinged myself to every 9 months I will replace these. Gotta think about the animals first!!!!! the cost is second.

MROK12

[bartstar]

Hi Ninong,

I stand corrected. I was not aware of the violet/blue degradation. It that true regardless of the lamp's CRI and/or kelvin temperature?

Can you refer me to any documentation. I'd like to research it further (it seems such a waste to throw away an expensive lamp that also contains toxic mercury).

I'm still learning.

Thanks

Bartstar

[Ninong]

Originally posted by bartstar:

Hi Ninong, I stand corrected. I was not aware of the violet/blue degradation. Is that true regardless of the lamp's CRI and/or kelvin temperature?

Generally, yes, but there are significant differences between Kelvin ratings and between different manufacturers.

Can you refer me to any documentation. I'd like to research it further.

Yes, I can refer you to testing that has been done by Dr. Sanjay Joshi of Penn State: http://www.animalnetwork.com/fish2/a.../2/default.asp

This is Sanjay's website. He has a few other articles on there about metal halide lamps and various ballasts that are commonly used in the hobby: http://www.personal.psu.edu/faculty/.../aquarium.html

[dattack]

Woops