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Re: Is this enough light?
On Fri, 28 Jan 2000, Wayne wrote:
>> One of the worst ones I found is a trigger start ballast with (2) 2'
>> NO F20 T12 CW lamp. This system as near as I can figure is rated at about
>> lumens per watt and produces a total of 1470 lumens with a nominal
>> of 40 watts. One of the best systems uses a Sylvania HL electronic
>> with (1) 4' NO F32 T8 841 lamp. This system produces 91 lumens per watt
>> a total of 3540 lumens.
>If you limit your selection of systems to a comparable price range, then I
>think you'll find the range in performance is much smaller. Also, in most
>instances we can limit our advice to systems that are either prebuilt or
>easily rigged up (like shop lights), because most of us don't have the
>knowledge or the tools to DIY a fluorescent system from scratch.
A high end system is really nothing more than a good ballast and decent
reflector and long T8 or T5 lamps. I do not think that it really complicates
matters a whole lot. If you like you can simply buy some strip light
fixtures with the electronic ballast already installed or you can go the AH
Supply route. (highly recomended) Also, you can retrofit an existing
fixture, this does require that you can read the wiring diagram on the
ballast but it is not all that difficult. Just don't forget to short the two
sides of a rapid start socket together if you are switching from a rapid
start ballast to an instant start ballast.
>Ivo Busko might have something more to say about this, but I think if you
>were making your comparison based on PAR rather than lumens you might find
>that the variations are not as great.
It actually would probably make the comparison worse. A CW lamp is
specifically designed to produce a lot of lumens but at the expense of good
color rendering so it has an unnaturally high lumen rating. I chose this
lamp for the comparison because of the non-RE phosphor lamps it is the
closest match in spectrum to an 841 lamp and is almost the highest lumen
lamp available in this size. I could have chosen an 841 2' lamp which would
have made the comparison more favourable but that would not illustrate the
difference between RE phosphor lamps and a regular Halophosphor lamp. There
is an improvement in efficiency obtained with the RE phosphors in the range
of 8% (I think) that has to do with the phosphors themselves rather than the
spectrum they produce. PAR is great for comparing lamps with different
spectrums but not needed when comparing lamps of similar or the same
spectrums in different sytems. The use of RE phosphors is part of the high
efficiency system and shouldn't be separated out.
>As an aside, the 2' lights with the standard preheat ballast may cost a
>third (or less) of the price for the high efficiency alternative, giving
>4410 lumens at the same cost as the best system. This would come with
>greater flexibility from being able to place the tubes in a variety of
>different configurations and from being able to mix and match different
>lights to get exactly the appearance you want. The low-end system would
>cost more to operate and tube replacement would probably be more
>expensive, depending on your choice of bulbs.
The only major extra cost of a high end system is in the ballast and they do
cost quite a bit. I just bought some of those 3 lamp Sylvania high ballast
factor ballasts for $50 can. each and I am going to use two of them on my
120 gallon tank. Typically you will save at least 1/3 on electricity over
using a magnetic ballast. Since Chroma 50s and T8 lamps are about the same
price and the T8s last easily 3 times as long, the lamp replacement cost
drops by 2/3. How long will it take to pay back my extra $100 investment?
If I hadn't built from scratch the system would have been just as cheap if I
had simply bought two 4 lamp fixtures and removed the guts for my project.
This would have given me a slightly less than optimum system but would have
saved me a few bucks and made the project quite a bit simpler. I just didn't
like the two extra lamps.
The biggest drawback of the high efficiency system is that you cannot easily
buy wide spectrum lamps for a high efficiency system. I mix three 850s with
three 841s and it seems to help but I am not sure how well it compares to a
wide spectrum lamp. OTOH many people seem to have equally good success with
triphosphor lamps although I believe this is probably just due to the fact
that the high efficiency system simply puts more light in a tank rather than
that the spectrum of these lamps is particularily suitable for growing