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Re: Replacing CF Lamps


Wayne wrote:

"There is no way a 96 watt PC is normally that much more efficient
fluorescent lamp setups."

TW wrote:

Then why am I able to grow swords and glosso under what would be about 1
watt per gallon, 2 watts at mid-day peak? And that's flat thick glosso,
the way. I think that the older lamps and reflectors were either not
good, both in terms of lumens and spectrum, or the 3 watts/gallon rule
wrong to begin with. Maybe some of both.

Wayne writes:

There is no "rule" for watts per gallon that will predict the amount of
light you will end up with based on the amount of watts you have. It is
just a guideline based on the observation that successful high light
tanks have between 2 and 4 watts per gallon. Different setups have a
huge variation in efficiency of putting light in a tank. Under AH Supply
kits are right at the top end of the scale but that does not mean that
other setups are not very nearly as good.

TW wrote:

"I have never seen any useful information on the spectral shift of
fluorescent lamps. I think it is mainly one of those aquarium myths."

Anecdotal evidence only. When the CF lamps got older, BBA increased.
However, there were other changes occurring in the tank that made a
relationship questionable. I'll watch for it again as the new lamps age
see if it repeats.


Wayne writes:

I might point out that as the lamp got older the main difference was it
produced less light.

To my eye 4 year old lamps have the exact same colour as new lamps.
Since plants are not at all picky about spectrum I doubt if they can see
a difference either. They fact that they will grow at all let alone very
well under the tri-phosphor lamps you are using is a testament to this.
Those lamps are pretty far removed from the spectrum of the sun. So I
figure so what if the spectrum shifts a little.

You know I think I could prove this one way or another just by taking a
picture of an old and a new lamp with a digital camera. Some graphics
programs could analyse each of the red, green and blue channels and then
I could see for sure if there was any difference. My bet is no
significant difference. I have some 4 year old 841s and I can go out and
buy a new 841 to compare.



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