Is it advisable to change Power Compact/T5 Tubes?

Yes definately! It leads to odd colors that favor algae IMO. if you dont. Once a year. When you buy new ones write the date in Sharpie on them so you know how old they are.

To look at this from a different POV --

Yes, over time the spectrum and output of fluorescent bulbs changes. But. If you have several bulbs over your tank, and your overall light level is more than sufficient, you can also just wait until they pop.

The manufacturers recommendation could be a bit... biased, you know. :icon_cool

Now if your lighting is borderline, or you have only one single bulb, or you want to keep changes in light levels minimal for some reason, by all means change them in regular intervals (and send me your used bulbs for recycling).

Hi sAroock,

Who is putting the asterisks or comments next to the bulbs recommending replacement at those intervals, the bulb manufacturer or the retailer? Power compacts have a shorter life expectancy than T5 or T5HO. Here is a post I did on another forum.

Hi ??????,

I thought you had a good question so I did some digging and this is what I found.

Table 1-3 illustrates features of four-foot standard T8 and T12 lamps. Standard T5 and T5 HO lamps have a rated average lamp life of 20,000 hours, the same as most standard T8 and T12 lamps. New prolonged-life T8 and T12 lamps have lives of 4,000 to 10,000 hours longer than T5 lamps. (Table 1-3 excludes these lamps.) The lamps in Table 1-2 all use RE80, a rare earth phosphor with a color rendering index (CRI) value of 85.

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20,000 hours sounds really great; but that is the life expectancy under optimum conditions. Useful life is usually about 80% of the life expectancy, after that there is degradation of the bulb output. Also the number of "on / off" cycles, heat (and cold), and moisture can further shorten a bulbs life.

BTW, 16,000 hours equals 2000 days (or 5.47 years) at 8 hours of use per day.

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I just changed my t5s out after one and a half years. The new ones are definitely brighter. Less brown too. I may have to raise my fixture a bit...

I have seen data that suggest that PC bulbs don't drop in intensity, after the first 2-3 months, for over 2 years. http://www.barrreport.com/showthread.php/5336-Some-Data-on-PC-Bulb-Life?highlight= I wouldn't even consider routinely replacing them after 1 year or 1 1/2 years. And, T5HO bulbs are supposed to last even longer. Changes in output spectra are extremely unlikely to cause algae problems, since algae are not, to my knowledge, triggered by certain spectral lines or the spectra in general. If anything, the slightly lower light output should reduce algae problems.

Hi Hoppy,

When Tom Barr was up here at GSAS in September he mentioned some of your work with lighting and PAR values. In fact, based upon what Tom discussed in his presentation, GSAS has purchased (and it arrived last week) a Apogee PAR meter so our members can quantitatively compare their aquarium light levels. If one member is doing well with a plant species with a certain light level, then members will be able to duplicate those conditions.

If we can assist in any testing/research you are working on, contact me and maybe we can help add to your data.

Seattle_Aquarist said:

Hi Hoppy,

When Tom Barr was up here at GSAS in September he mentioned some of your work with lighting and PAR values. In fact, based upon what Tom discussed in his presentation, GSAS has purchased (and it arrived last week) a Apogee PAR meter so our members can quantitatively compare their aquarium light levels. If one member is doing well with a plant species with a certain light level, then members will be able to duplicate those conditions.

If we can assist in any testing/research you are working on, contact me and maybe we can help add to your data.

Click to expand...

Thank you for the offer! PAR meter readings are good only when you include the distance from the sensor to the bulb, which light fixture it is, and what bulb. Most of what I have done has been with a variety of different bulbs, all combined together. But, there really is a lot to learn comparing the different color temperature bulbs, different manufacturers bulbs, different age bulbs, different light fixtures/reflectors, different numbers of side by side bulbs, spaced at what distance, etc. How to present such data is something to think about too. Possibly, PAR numbers all at the same distance between bulb and sensor - 20 inches, for example.

My local reef club owns a par meter, and they were trying to debunk the myth regarding bulb falloff (in reef circles T5s last 9-12 months, PC 8-9 months and MH last a year tops). They found that Halides at 12 months have lost 15% of their output, but T5s and PCs at 12 months are within 5%, which is reasonable considering it wasn't the exact same bulb.

Seattle_Aquarist said:

Hi sAroock,

Who is putting the asterisks or comments next to the bulbs recommending replacement at those intervals, the bulb manufacturer or the retailer?

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The manufacturers, some have it on their packaging.

Well so far , so good. I guess there's still some juice left in my tubes, I might replace them later on.
thanks for all the replies.