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Re: Flourescent Lighting Options?



David wrote:

Recently I've been contemplating building my own hood to go over the top
of
2 side by side 10 gallon aquariums. I've been doing some reading on the
subject and see a lot of people designing their own lighting systems
from
scratch, including ballasts, lights, reflectors etc.

Now, I am by no means a lighting expert (I consider my decision to
purchase
a Chroma 65 bulb for one of my tanks my greatest lighting
accomplishment)
but why wouldn't it be possible to buy one of the pre-built kitchen
style or
garage style lighting systems and just put in good bulbs?

Am I being na´ve?

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You can buy some really good light fixtures that are not designed for
aquariums. One of the big advantages of doing this is that you will know
what you are getting. A good light fixture company will publish
photometric data, including LER, ballast factor, fixture efficiency,
fixture lumens and light distribution. Ironically, to my knowledge there
is no compant that sells light fixtures for aquariums that supplies any
of that data.

You can buy light fixtures with PCs, linear T5s, T8s and T12 lamps with
or without specular reflectors. Any of the fixtures suitable for
aquarium use will be special order and quite expensive. The trick is to
find a a suitable fixture from the vast array of possibilities that
doesn't cost a whole lot. You want a fixture that will produce a lot of
lumens for it's size and one that is still quite efficient so you can
save on electricity. You want a fixture that will direct as much light
as is reasonably possible down into the water. You also need one that
will accept readily available lamps that have a suitable spectrum for
growing plants. AH Supply appears to have the best designed aquarium
light fixture but any 2 lamp fixture using T8 lamps and a high ballast
factor with a good reflector will be very nearly as good. AH Supply
fixtures are more compact, have efficient electronic ballasts and will
direct light into the aquarium better but the lamps are quite expensive
and the lamp efficiency is fairly low. A good twin tube fixture with a
6" wide powder painted difuse reflector can be bought at Home Depot and
suitable lamps are very inexpensive however T12 fixtures are inefficient
and very large for the amount of light you get. The problem is that
large diameter lamps block too much light within the fixture, the
ballast is magnetic and not electronic and the ballast operates at a low
ballast factor which means that relatively little light will be produced
by the lamps.

The easiest fix for this is to simply buy a 4 x 32 watt ballast and
replace the ballast that comes with the fixture and use T8 lamps instead
of T12 lamps. The ballast has to be wired up in a non standard way but
basically all you have to do is run a blue wire to each pin of lamp #1
and a red wire to each pin of lamp #2. One yellow wire to each pin at
the other end of lamp #1 and one yellow wire to each pin of lamp #2. It
is best to use 32 watt, 25 watt or 17 watt T8s when you do this. Those
lamps are a bit hard to come by so you can use 20, 30 or 40 watt T12s or
18 or 36 watt T8s instead but you will not get as good a result. This
also works best with 4' fixtures as the components are much easier to
find. You can cut down a 4' fixture but the best lamp selection of cheap
lamps is in the 4' lengths.

The resulting fixture when using the T8 lamps will rival an AH Supply
fixture for light output. Each 4' T8 lamp will have a light output of a
50 watt PC. It still takes up more room than the PC though.

So the short answer is no you cannot easily buy a ready made fixture at
a hardware store that will suit your lighting situation as well as an
aquarium specific fixture. Specifically an AH Supply fixture. You can
create a fixture but that is best done with 4' tanks. You can also just
cram as many T12s as possible into a hood and hope for the best. This
works best with longer tanks of 3' or more. Short T12 light fixtures are
so inefficient there is a fairly low limit on the achievable light
levels no matter how many lamps you use.

Wayne