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Lighting
Rod wrote:
Good morning folks. I just started building a hood for my tank. After
just
about $400.00 (can) I have everything I need. Unfortunatly I didn't come
here and ask a few questions first and now the hood is built. But I
would
like to know the depth of (and cost of) my error so as to not to repeat
this
on my next tank.
First off I made two sections of the hood each 5" high. The bottom
section
drops 1" over the aquarium side. And the top is hinged onto this. Now
what
I'm wondering is;
I write:
This is very similar to how I build hoods except the bottom section
hangs down about 2" below the top of the tank and is only a total of
about 3" high. This gets the lamps closer to the water.
Rod wrote:
1) Is having my T12 bulbs 7" above the surface of the water going to
be
too much light loss? How much will I lose? I have purchased some sheet
aluminium to fashion a reflector. I probably can get it down to around
4"
from the surface. Will making these adjustments make any signifcant
impact
on the lighting arrangement?
I reply:
I think they will. You must use the most reflective material possible
for it to be of much benefit. I use aluminum sheet as a combination
socket holder and reflector. I buy the heavier guage white stuff that is
used for aluminum flashing. It really stands up well under aquarium
conditions. I cut 5/16 x 1" notches into the edges of the alumnium to
recieve the lamp sockets. If you buy replacement sockets they have screw
that can be used to fasten the socket to the sheet as well. By arching
the aluminum sheet you can make it strong enough to support the lamps.
This is not really a reflector but more of a reflective backing for the
lamps. It is impossible to build good specular reflectors for T12 lamps
in the space you have in an aquarium so I wouldn't waste time like I did
trying to do it. The reflectivity of the hood surface and minimizing the
reflective area of the hood enclosure are the main concerns.
Rod wrote:
2) I have designed it to use 6 bulbs for a total of 240 Watts. Is this
enough for a 80 gallon tank? I'm actually using the measurment of a 70
gallon tank as I have at least 4" of substrate and I'm sure that I lose
10
gallons or more. From the tank surface to the substrate is 16.5 inches.
I
could still make the change and add in 2 more bulbs for a total of 320
Watts. Would this be overkill?
I reply:
The amount of light that you will get from 8 lamps is not proportional
to the amount of light you will get from 6 lamps. The more lamps you
pack in there the less each lamps contributes due to restrike. This is
the main disadvantage of T12 lamps. They have a large cross section and
you can only put in so many before additional lamps just don't provide
more light. I would go with the 6 lamps. It should be enough for almost
any plant. Many people are very successful with 6 lamps on a 75 gallon
tank. The ballast you choose will have more of an impact than the 2
additional lamps.
Rod wrote:
3) I have bought 2 3" muffin fans (cooling fans) to mount into the hood.
I
will wire them to go on and off with the lights. This should be enough
cooling for 6-8 T12 bulbs?
I reply:
If the ballasts are remote mounted you shouldn't need any cooling. I
would rather make the effort to remote mount the ballasts rather than
mess with cooling fans.
If you are intending on using a glass cover then you do not have to be
so careful about protecting your hood from moisture. If you do not have
a glass cover then it is almost mandatory that you epoxy the inside of
the hood. High humidity does terrible things to paint finishes and wood.
It is a lot of work to make a hood even for someone like me who makes a
living working working on stuff like this. Protecting your effort and
expenditures with $20 worth of epoxy is a wise investment. I have made
several versions of this type of hood and I am now quite satisfied with
the design. It is more of a challenge to make than other styles but well
worth the effort I think.
Wayne