Re: new MH lighting

Keith  Breedofish at aol_com wrote:
> Hello everyone...   I just purchased a 175W MH Pendant...   Cheers....   It
> is for a 55 gallon (48x12x18) tank.  When I hooked it up and hand-held it
> over the tank, I was less than impressed with it.  It seemed to only light
> the center of the tank and none of the sides.  Is this common or am I doing
> something wrong.  It also didn't seem as bright as my former 80w of FLs.  I
> heard that the MH is much more of an intense spotlight, while the FLs are
> more of a 'coverage' light.  Does anyone else have any experience with this?
>  Just for note:  my entire bedroom is lite up by the MH now, and I'm thinking
> about building a 'fence' around the top of the tank to shield the rest of the
> room and make looking at the tank bareable, is this feasible?  

What shape is the pendant reflector? It should be parabolic and deep; that is
taller than it is wide. The bulb needs to be situated well inside the
reflector such that the light comes out in a cone the edge of which comes
close to the end of your tank (at the level of the substrate). This will
create lower light intensity at the ends of the tank which is where you can
situate Echinodorus, Java Fern or Crypts. There will also be some reflection
from the opposite side of the reflector so even if as you are seated in
the viewing room, you won't be blinded by the direct light from the inner
bulb, it can be somewhat annoying if you like to view the tank from a seated
position too close and too low. A 4'x 1' tank is not ideal for a single MH
since the light cone is circular. I put some house plants on a stand in
front of the tank to take advantage of the light spilled over the front but
that can be a nuisance too.

If you have the deep hyperbolic reflector but the bulb is mounted too low,
you could add an electrical junction box or two to the top and remount
the ceramic fixture deeper (or get another reflector). The larger the
reflector the better. You can always move the pendant up and down on chains.

If you have a safety lens mounted on the bottom of the fixture especially
if it has a "pebbled" or frosted surface, this will diffuse the light
and helps avoid an uncomfortable glare esp. if the pendant is mounted high
in the room due to a tall tank.

Before I had a proper reflector on the 50g tank I used tinfoil to help
shield the eyes; tacky but it works. I'm sure there are better methods
if one has the time and materials to be inventive.