How do you tell a bulb needs replacement?

lazarus

lazarus

Member
I have T5 PC lighting (8 bulbs, half white, half actinic) over my 110g FOWLR & soft corals DT. A year ago, I noticed corals dying and discovered that a couple bulbs went out, so I assumed that was the reason. The LFS suggested I replace bulbs annually suggesting that they go bad even if i cannot tell, but that is an expensive proposition at almost $20 each. Its been a year since that episode and I dont see any degradation in the bulbs, but maybe my eyes cannot distinguish.
Does anybody follow the one year replacement rule recommended by LFS or do you wait til you have a burnout.
 
spanko

spanko

Active Member
Bulbs over time, all bulbs MH PC T5, lose spectrum necessary for coral growth. Not visible to our eyes but non the less gone.
 
subielover

subielover

Active Member
I would. Reason being, as bulbs age their spectrum changes into a much more algae friendly lighting spectrum. Bulbs are one thing I figure on replacing at least once a year.
edit:yet again Spanko beats me to it.
 
subielover

subielover

Active Member
If you are speaking to me, no I can't actually. It is just what I have come to believe as "the word." What are your thoughts as to why we must change bulbs?
 
bang guy

bang guy

Moderator
I also can only speak from opinion. I believe that as a fluorescent bulb gets used the phosphors wear out. As this happens the bulb produces less light. Eventually it's producing a LOT less light and should be replaced so the corals can receive more light.
I think a specific phosphor generates a certain spectrum of light. I'm not sure the spectrum changes as the phosphor ages, I think it just stops working.
 
spanko

spanko

Active Member
Quote:
"One of the problems with fluorescent light sources is that both their intensity and spectrum change with age. This is especially true of HO and VHO fluorescents. The decrease in intensity could cause reduced growth rates of both corals and algae, while the spectrum usually shifts towards the red end which can lead to breakouts of undesirable algae. These bulbs should be replaced at least once every six months, even more frequently if reef-building hard corals are kept. "
From the article contained here http://www2.hawaii.edu/~delbeek/reefaq4.html
 
ajer

ajer

Member
All T-5s, PCs, T-12 etc. have mercury in the tube. When electricity is run through the mercury, it fluoresces UV. The tube is lined with Phosphors which convert the UV into different wavelength (hertz) visible light. Tri-Phosphor tubes for instance have 3 different phosphors emitting light at 3 different wavelength (hertz). Some phosphors "burn out" before others, causing the tube to emit too much light of one type and too little of another!
 
bang guy

bang guy

Moderator
Originally Posted by Ajer
http:///forum/post/2893868
All T-5s, PCs, T-12 etc. have mercury in the tube. When electricity is run through the mercury, it fluoresces UV. The tube is lined with Phosphors which convert the UV into different wavelength (hertz) visible light. Tri-Phosphor tubes for instance have 3 different phosphors emitting light at 3 different wavelength (hertz). Some phosphors "burn out" before others, causing the tube to emit too much light of one type and too little of another!
Ahhhh OK, that I can believe. That makes perfect sense, thank you!
 
spiderwoman

spiderwoman

Active Member
I can only say from experience with MH bulb. Your tank is taken over by algae! I let my MH light in the 75g reef go unchanged 3 months over what I had planned and I'm now fighting nasty algae there. Bulbs were changed yesterday.
 
bang guy

bang guy

Moderator
Originally Posted by SpiderWoman
http:///forum/post/2894464
I can only say from experience with MH bulb. Your tank is taken over by algae! I let my MH light in the 75g reef go unchanged 3 months over what I had planned and I'm now fighting nasty algae there. Bulbs were changed yesterday.

I know for sure that MH bulbs change spectrum as they age, it was fluorescents I had a question about. The multiple phosphors explains it well.
 
You must log in or register to reply here.
Top