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Fluorescent tube substitution question

Posted by AlanRoberts z7b NC (My Page) on
Wed, Feb 9, 05 at 9:20

I could use some advice from fluorescent tube/fixture experts here. My space-limited seed-starting space wouldn't support the use of the classic shop-light solution, so it was setup using multiple single-tube fixtures from Lights of America (simple U-shaped plastic fixture with switch and line cord, whatever the starting scheme is there isn't a lot of weight in the switch/electronics end).

The fixtures came with F20T10CW tubes, branded Lights of America. There are pretty hard to find, and my memory from the last time I purchased one is that it was costly.

A Phillips Altos F20T12/D fits in the fixture (with less air gap between the tube wall and the base of the fixture) and starts. The light color seems very different from the other tubes, which didn't really surprise me.

Any thoughts/advice, pro or con, about using the T12 tube in this fixture? My biggest concern is whether the increased diameter of the tube represents a overheating/melting/fire threat for the fixture, and there may be other issues I don't know enough to ask about.


Follow-Up Postings:

RE: Fluorescent tube substitution question

  • Posted by GaWd z9/10 NorCal (My Page) on
    Wed, Feb 9, 05 at 11:31

If you're concerned about heat, and the size of the bulb, why don't you experiment with a T8 bulb and see if it starts. It's smaller in diameter, and more efficient, so it might run cooler.


RE: Fluorescent tube substitution question

If you are using a 2 foot light, the best way is to buy 2 two foot, two tube fluorescent light strips for 15.99 each. If you have a Home Depot around. Buy two ballasts that are marked ADVANCE REL-4P32-SC for 17.98 each. Then buy 4 two foot T8 tubes which can be spendy!

You will see bright results.


RE: Fluorescent tube substitution question

"My space-limited seed-starting space wouldn't support the use of the classic shop-light solution"

Well, it depends on how 'handy' you are... but you could buy 4 foot shoplights and cut the fixtures down to 2 footers.

Metal snips, sandpaper for rough edges, heavy pliers, etc. Since there are decent electronic shoplights for $7.25 now, it might be worth the effort.

Or you could think about getting really creative and going vertical with the regular 4 foot light fixtures if that would fit your space better.

Imagine having the lights vertical and using reflectors over your shelves to bounce the light back down to the plants.

You can get a kind of plastic with mirror backing for the baffles, it's pretty good and not as heavy as glass.

Or just use cardboard with aluminum foil taped to it to bounce the light around.

RE: Fluorescent tube substitution question

Jkirk ... Sorry, I wasn't clear enough in my original post. The solution is already built, using eight (4 per shelf) of the single-tube Lights of America fixtures, mounted on a lightweight crossbar scheme that lets me adjust the horizontal spread between fixtures, and then raise or lower the entire set of fixtures using chains and S-hooks.

After my first tube failure last year I discovered the relative lack of supply and cost issues for F20T10 replacement tubes. I can get a replacement with somewhat more driving. I just wanted to know if there are: inadequate brightness / zaps tube / melts fixture / catches fire kind of problems with using a different F20 tube, since a less-expensive F20T12 fits (barely) and starts, and a (presumably?) less-expensive F20T8 would fit (easily?) and might start.

Going vertical is a fun idea, but I think it would exceed the tolerance of my spouse, and I really don't want to start enclosing the shelving with a lot of reflector area ... I've got a fan running to help avoid damping-off problems and toughen up the little seedlings for the "real world"; don't want to block any of that airflow.


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