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RE: lighting a 90G tank
Daphne has some questions about lighting her new tank...
> A) One 175 watt MH fixture (horizontally mounted and probably from
> Hamilton) and Iwasaki 6500K bulb which would give me 1.9 watts per
> gallon, perhaps a 250 watt would be better... that would raise it to
> 2.7 watts per gallon.
One 175 watt MH is probably not going to be enough light for a 90 gallon
tank, and _any_ MH bulb is going to get really hot, so your hood had better
be well ventilated. But you just can't beat the "look" of MH - it has a
sparkling quality that can approximate sunlight streaming down through the
water column, a very beautiful effect.
> B) PC lighting. If I understand correctly, the retrofit PC fixtures
> from AH Supply can be mounted in my hood and no additional
> hardware/ballasts/etc are required. I can fit two 96-watts, one
> 55-watt and one 9-watt (depending on exactly how much space is required,
> I possibly could replace the 9 watt with another 55) The initial
> description would give me 256 watts which would be 2.8 watts per gallon
> if the second were possible, 302 watts which would be 3.3 watts per
The retrofit kits from AH Supply are simply super. I just replaced 3 175W MH
pendants over my large tank with 6 55W PC tubes. The relectors supplied by
AH Supply are the best I've seen and if you are at _all_ handy with a
screwdriver you can install them in your hood with ease. They come with very
clear instructions. As for how many you can fit over your tank, AH Supply's
web site gives the exact sizes of the various relectors, and if you can't
figure out the maximum wattage you can fit into your hood, just ask Kim -
he's very helpful.
I'd recommend the 6700K tubes - they have a "super white" look that comes
very close to giving me the "sparkle" that I miss from the MH bulbs (close,
but no cigar...)
> 1) Noise. - This will be in my great room and a hum from the ballast
> won't be welcome. Also, the ballast from a MH would have to be located
> under the tank, there is nowhere else to put it which raises the heat
> issue in #2. Not sure if the PC ballasts is on the fixture or remote...
MH loses big time here - I originally paid big bucks for national brand MH
fixtures and the ballasts were so darn noisy I had to knock a hole in a wall
and put the ballasts in a closet next to the aquarium. The PC ballasts sold
by AH supply are tiny little things that will fit anywhere and run
> 2) Heat. - I will have a muffin fan installed and the hood will be
> vented but am concerned about heat from both the bulbs and ballast (in
> the stand).
MH loses here as well. PC tubes will get warm, but nowhere near as hot as a
MH bulb, especially a 250W monster.
> 3) Quality. - I know CRI needs to be high to more closely approximate
> sunlight and temperature is important as well so I guess my question is
> this, is the quality of the Iwasaki 6500K bulb as good/better/worse than
> the 6700K PC? I have seen articles in the past that seemed to indicate
> the MH's have a better quality of light (more closely approximates
> sunlight) as opposed to the PC's, yet I have seen contradictory
> information that stated just the opposite. Perhaps it depends on which
> you are selling he, he : ) ! Is 250 watts of 6500K MH equal to 250
> watts of 6700K PC?
Neither your plants nor your eyes would be disappointed with either bulb.
> 4) Depth. - Is either set-up going to be better/worse than the other in
> terms of being able to provide adequate lighting in a 24 inch deep tank?
> Can one "punch" as deep as the other?
Given similar wattage, yes. The quality of the relector has a lot to do with
this - and as I've said, AH Supply's reflector design is excellent.
> 5) Equipment. - The ballast thing still isn't clear. Don't the
> fixtures have one or is it inadequate etc...
What isn't clear about the ballasts? If you go the PC route, the ballasts
come with the kit and are working fine for me and I have never heard a
contrary word about them either here or on USENET. MH ballasts, on the other
hand, seem (to me at least) to require either an "advanced tinkerer's"
degree or that you have an electrical engineer on staff. They are big, noisy
and hot, as well as being _expensive_. And I'd really rather fry my eggs in
a frying pan, not on the top of a MH Ballast <g>.
As you can probably tell, while I love the _look_ of MH lighting, and love
the idea of an open tank, I really like the new PC tubes and fixtures.