How often do you need to replace Compact Fluorescent bulbs?

[slipstreamv2]

I came across this on the web:

"There are rumors running around the Internet that you need to replace your fluorescent tubes every year or so. I feel that is a myth. If you have high quality compact fluorescent bulbs you can run them till they drop. "

http://rexgrigg.com/light.htm

Do you guys agree/disagree?

I have some 55W bulbs I got from ahsupply a couple years back. I used them for about maybe 6 months, and they've been unused since then. I'm wondering if I more than 6 months of life in them.

I also have some that were never used...I'm thinking those should be as good as new.

[TwoTankAmin]

I use all AH Supply kits and bulbs on several tanks- 36w and 55 w bulbs. One is a high light co2 added tank. I have always used the bulbs until they burned out. The oldest tank is going on 6 years. My best guess is I get between 18 and 20 months out of a bulb before it dies and run them an average of 12 hours/day.

Never used = New :-)

The only standard fluor bulbs I dont replace annually are the no longer available Triton Full sprectrum tri-phosphor ones which are usable til they burn out. I believe standard fluors degarade over time in a way not visible to our eyes but in a way that does get used by plants. If you dont have live plants in a tank you can run the same standard fluor bulb for a long long time.

[Mgamer20o0]

burn out....

[slipstreamv2]

Good to know, thanks.

[tanker]

I agree, unless you raising plants.

[Slappy*McFish]

I replace saltwater and plant lights every 6-12 months.
All other lights are replaced when the ends of the bulbs begin to darken/blacken.

[slipstreamv2]

I agree, unless you raising plants.

Sorry if I didn't make it clear, this is in regards to planted tanks - fluor. tubes becoming ineffective for plant growth (even though visually, their light output is fine).

Would love to hear more opinions, especially backed up by facts or even anecdotal evidence.

[bigwater]

I have been running 4-55 watt bulbs on a 90 for a little over 2 years and 1-55 on a 29 for about 4 years. All of the equipment came from AH Supply and I think the owner told it that they needed to be replaced once a year for best plant growth. I have run the bulbs longer than that, and when I replaced them the ends were black. The new bulbs seemed to make a big difference. I am not consistent with keeping up on the water changes and fertilizing so I may not be the best judge. BTW, I ordered all new bulbs over two weeks ago from a online huge bulb store to save a couple of bucks and I am still waiting! I should have ordered from AH, lesson learned. So if the new bulbs ever show up I can pay closer attention the bulb difference and report back.

[Quartermain]

Here is graph depicting lumen depreciation for various bulb types over time...

http://www.mge.com/business/saving/madison/LI_01.html

It doesn't show any values for what we call "power compacts" or linear compact fluorescent bulbs. But if we Google "CFL lumen maintenance" we find that compact fluorescents in generally (whether they are self-ballasted spirals or externally ballasted linears) are more or less just as efficient as any other NO bulb type with an overall lumen depreciation of around 15% - 20% over the bulb's rated lifespan.

The argument has been to stagger bulb replacement so as to keep light at a consistent level thus avoiding a potential situation where you could introduce so much light with the new bulbs that you give algae an opportunity to ravage your tank. This definitely should be done if you're running MH or VHO which can depreciate by as much as 60%! But it's not necessarily required for normal output fluorescent bulbs such as PCs... this is assuming of course that you're not overdriving them.

So let's say our bulbs burnt out and we need to replace then both. A sudden 20% increase in light is not going to put you in jeopardy of having a major algae outbreak. You might see a little more algae grow on the glass at the end of the week.. if you're really unlucky. More than likely you'll just see noticeably better growth with your plants.

So yeah, I think Grigg is right in this case. PCs and other NO fluorescents probably can be used all the way up with no real concern about plant health or algae outbreaks.

[tanker]

I replace my PC over my FW every 12-14 months. Many years ago (I used my Fathers "Luminometer??) to check bulb life. There is a big drop after about 10 months. I like my plants and I know bulbs are expensive.....so....I replace.

[vidiots]

Hahahaha, I'm glad to see that I am not the only one who is too cheap to replace the bulbs on my plant tanks before they burn out.

The only way to know the effect for sure would be to measure the output over time with a light meter, and most of us don't have one of those.

I figure if the old bulb is still working and the plants are still growing why fix what isn't broke.

[slipstreamv2]

Sorry for the late response.

Quartermain - thanks for the link. According to that chart, the bulb would simply die before lumens decrease significantly as a %.

Tanker, interesting counterpoint. How significant was the drop, %-wise, after 10 months - 50%? You said many years ago...I wonder if bulb technology has resulted in today's bulb output remaining much more consistent.

[tanker]

If memory serves me..there was about a 30% drop after about 10 months. I did not do much measuring after that. This was when I was just using regular fluorescent bulbs. I now use PC bulbs.

I do not think bulb technology has changed much over the years. These bulb still use mercury vapor which glows when charges and the coating used on the inside of the bulb effects the spectrum. Same as before..

[Squawkbert]

Here is graph depicting lumen depreciation for various bulb types over time...

http://www.mge.com/business/saving/madison/LI_01.html


*If* "slimline fluorescent" = PC, and you
1) are OK w/ 80% of original output
2) run 10hours/day,
the line ends at 12000H. That'd be 3.28 years. I'm on my 2d PC bulb (1st one broke 3 months in) and will run it until it, or some plants die...