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Re: replacing CF bulbs

Authur wrote:

Anyone have any advice for changing CF bulbs?

Do they lose lumens over time like NO bulbs?  Or is it
non-significant?  Should I just wait til they burn
out?  What's the longest someone has had a CF bulb


I reply:

There is no way to predict when an inividual lamp will have to be
replaced. CF lamps vary widely in how well they maintain lumens from
lamp type to lamp type and even within each lamp type there is a wide
variation. Under laboratory conditions, good quality 55 watt PC is
supposed to maintain 85% of it's lumens throughout it's operating life
(usually about 12,000 hours) . The ballast, lamp coating and ambient
temperature will have a strong effect on this however.  T8 lamps will
generally maintain 95% of lumens for 20,000 hours while VHO T12 are so
bad that they will lose 30% after 40% of their short lives.

For aquarium purposes, it is very important to look at the lumen
maintainance characteristics of the lamps you are using. You have to
design a system that provides more light than you need so that after
about a certain percentage of the lamps rated life you will still have
sufficient light. Otherwise, you will be constantly replacing lamps. You
really want to pick the light level you want at the time you intend to
replace the lamp. This is not a consideration with most T8 lamps they
can go until near failure but it is somewhat true with PCs and with VHOs
and MH it is huge.

I notice that Phillips has introduced a new 80 watt PC. I also notice
that it only has a rated life of 10,000 hours. I bet that the really
high wattage 96 watt PCs are even worse.