Re: GE sunshine no shine

["Wayne J" <w.jones at sympatico_ca>]

Scott wrote:
Imo, if you don't toss them at 6 months and you keep them
for over a year, as I do, you might notice that there's
plenty of life left in those bulbs.  I think the
6-months-and-throw-away-a-perfectly-good-bulb rule started
with the reefers, whose tank inhabitants are sometimes much
mre sensitive to specific wavelengths, and in need of much
more light.  I think also that it started with VHO bulbs,
although the plants still like them long after the 12 month
mark.
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I very much agree. You should only throw your lamps away when they don't
provide enough light anymore. I have lamps that are 6 years old and still
going strong. There is quite a bit of confusion between lumen maintennance
and lamp mortality. They are basically unrelated issues. All lamps have the
potential to fail nearly immediately or to last long past their rated hours.
In the case of these Chroma 50s the lamps failed prematurely. I don't know
the reason why but it could be an incorrect ballast, bad ballast or a
manufacturing flaw. Chroma 50s like all NO T12 lamps do have an electrode
that is susceptable to failure when overdriven.

Lumen maintenance is something else altogether. If a lamp does not fail then
it will maintain it's lumens according to a lumen maintennance curve. Those
curves typically drop off quite rapidly in the first 100 hours and then as
time passes the lumen loss becomes less and less significant. For most lamps
there is a limit on lumen loss that is not far below the lumen output at 40%
of rated life. If you have kept a lamp for that length of time then you
might as well just keep it until failure as the lumen loss won't be much
greater after that point. For certain types of lamp ballast combinations
this is probably going to be well over 5 years. For other types of
lamp/ballast combinations this is going to be only 6 months.

If you do not have a Lux meter to check light levels, then the best clue as
to when to change the lamps is end blackening. My 6 year old lamps have
about 2" of end blackening at each end which leads me to think they are
getting due to be replaced. The lumen output of the 6 year old lamps is only
about 10% lower than my 1 year old lamps.  I could use a bit more light so I
will be replacing them soon in any case.

With MH lamps and reef tanks there is also the problem of spectral shift.
Certain MH lamps will dramatically change colour over a period of a year or
so. I doubt if this would be a problem in a planted tank but it seems like
it could be for a reef tank. Yet another reason why reefers might have to
change their lamps more often.

Lastly there is the issue of profit. It certainly dos not hurt a retailer to
promote the idea that you should change an expensive specialty lamp every 6
months. You will notice that you won't find any data such as mean lumens,
design lumens or a lumen maintenance curve for those types of lamps, even if
the lamp is just a relabelled warm white. Selling someone an aquarium is not
likely to be all that profitable but selling someone a new lamp with a huge
profit margin every 6 months is just pure gravy. All the profit is in the
consumables. Plant fertilizer, new lamps, new fish to replace the fish that
newbies kill, pH adjusting chemicals, special additives to use during water
changes, useless medications and so on.

Wayne