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[APD] Failed CF Retrofit - Don't let it happen to you!

Greetings to all list members from a new subscriber!

Well, I should have consulted this list first, I think I wasted a lot of
time and money. I designed and retrofitted my own light hood and it appears
to be both inadequate and faulty.

We have several vintage Metaframe tanks, stainless steel corners, slate
bottoms. Also have a couple of matching Metaframe stainless steel light
fixtures, some as a full hood, some just the light (incandescent). We really
enjoy the "retro" look, especially when they are kept on their contemporary
wrought iron stands.

Obviously, these 40 year old light fixtures are pitifully inadequate, so I
got it in my head to design my own retrofit for one of the fixtures that fit
our 20 GH as an experiment. Well, spatially and aesthetically, the
experiment was fairly successful, but the performance is a failure.

I took my first creative cues from the existing incandescent design. This
was a double socket mounted in the center of the canopy, so that the bulbs
were held horizontally, opposite each other. I began to search for compact
fluorescent lamps of high luminous intensity that could occupy roughly the
same amount of space as the incandescent bulbs. I settled on 42W GE Biax T/E
(F42TBX/840/A/4P). Once my special order came in at my LES, in exchange for
approximately 100 greenbacks, I had the 2 aforementioned lamps, the 2
GX24Q-4 lampholders (Leviton H42A), the electronic ballast (Advance
ICF-2S42-M2-LD), a new nickel-plated canopy switch, 8 feet of 14-3 appliance
cord, and a rubber grommet (which I had to buy 5 in the blister pack).

I took it all out to my shop, dug out some wire nuts and a wall socket plug,
and put it all together. I had originally intended to have the ballast
remote from the fixture, on the floor, but it was so compact and cute that I
mounted it piggyback outside of the reflector. I fabricated mountings for
the lampholders. The two small bolts that held the ballast on also held
these metal brackets in place and provided a fastening point for ground. In
the end, I only needed to drill 3 new holes in the stainless steel shell and
enlarge the existing zip cord hole.

As I peered into the now-shadow-free reaches of the aquarium, I was
extremely pleased with myself. With output rated at 3200 lumens apiece, I
thought, "Wow, 6400 lumens. You are awesome."

Well, about 2 hours later is when my bubble burst. I heard a loud TIC! When
I surveyed the situation, I found the 3/16 inch thick canopy glass beneath
the fixture had cracked. My wife said, "I told you it was too hot!" Being a
male, I said, "Don't worry, I told you, they are designed to run that hot. I
just made the mistake of keeping it too close to the glass." I went out to
the shop with some supplies we had on hand and came back in with 4 feet made
of cork that slipped on securely; not only holding the light at a safer 1
inch distance away, but also provided extra stability and slip resistance.

So far so good. The canopy glass was a bummer, but I figured, "You gotta
break some eggs if you want to make an omelet."

Two days later. Enjoying a bright tank with some new plantings that were now
possible. Push the switch in the morning and just a brief flash - then
nothing. Testing revealed that one of the 12,000 hour lamps had already
burned out. Now I was really crestfallen.

I decided to do the research I should have done before throwing my money
out. My wife was right -- boy, that right there really hurt! :-(
The fixture was too hot. Being open at the bottom only was not enough.

But I found out more than that, and that is why I turn to you folks for
help. These 4000K lamps are the brightest color these 42 watters come in.
Not even enough for good sustained plant growth in the first place.

So finally I get to my question. I want to go back to the drawing board.
What type of suitable lamps can I put in this hood as it is?

Inside, it measures 23 inches long, 3.5 inches wide at the bottom, 1.5
inches wide at the top and 2 inches high. Cross sectional shape like this:

/  \

I'm guessing that I will need to provide some openings in the top for
cooling by convection, no matter what type of lamp? One possibility was to
drill multiple holes close together on a grid spacing. Any thoughts on that?
I wish I could do something without compromising the original outward
appearance too much.

I will be stockpiling the parts from the current "experiment." Is there any
sense in making plans to incorporate these parts in a future from-scratch
hood design for a bigger tank, like a 55G? I mean, what lamps could be
paired with these to give an acceptable spectrum for the future. The ballast
can run 1 or 2 of these bulbs.

Thanks so much for any light you can shed!  ;-)

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