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Re: Aquatic Plants Digest V3 #312
> Subject: Lighting for a 100G "long"
> Hi folks,
> I'm getting ready to set up the 100G "long" tank that I "inherited" last
> I'm considering my various options as far as lighting is concerned. While
> I'm a big fan of T-8 lighting, the 6' length of this tank makes T-8
> lighting a bit tricky. The better color temperature bulbs seem to be
> available only in the 4' lengths. This means I would either have to
> stagger the bulbs and mix them with 2' bulbs, or live with color
> temperature bulbs that are not really to my liking.
> A pet store near me can get me a reasonable deal on a 6' VHO fixture that
> would do the job, but I'm also considering an open top tank with MH's,
> since I love the look of open top tanks, and I _think_ my kids are past
> drowning age.<g> My questions are:
> 1. The tank is 18"x18"x6'. Anyone else working with this size tank? What
> are you using for lighting, and what do you like/dislike about your setup?
Two 175w MH bulbs should be plenty for the tank you describe. I much
prefer the effect from MH over flourescent. I had a tank like you
describe only 22" tall that used fl lites with some offset to each side
and an overlap in the middle.
> 2. I'm assuming that with this size/shape tank, that I'd want to go with 2
> 175W bulbs?
> 3. How high would they have to be hung to avoid burning emergent leaves?
Good question. I have mine about 14-18 inches above the water. I do
not grow emergent plants. That distance is from the BULB to the WATER.
My tanks with 250 w MH are a little over 2 feet from bulb to water.
However, it is important to consider the "can" or reflector. Mine are
cheap semi-diy from Aquatic Lighting systems ($100 for 175 watt and
about $150 for 250 watt). You have to wire them together and they are
not as pretty as the commercial pendants. Can shape determines the
focus of light and ideally you want the light focussed so it does not
spread beyond the width of the tank. This can be more of a problem if
the can is hung too high. I like tall cans that hide the bulb up in the
can so when you are sitting down you are not blinded by the bulb. I
have called Jeff Katz at ALS and ordered some new cans to replace a few
where that is a problem.
Remember the inverse square law doesn't work here. Can design will
determine the light spread.
> 4. This tank is going in my livingroom, and I want people to be able to
> sit comfortably nearby without being blinded by the light. Any suggestions
> on the best way to keep the light headed into the tank and out of the rest
> of the room?
Hope this helps, Karen.
Earle Hamilton Aquatic Gardeners