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Question about my lights

Posted by tastefullyjulie zone 6 (My Page) on
Tue, Feb 21, 06 at 13:28

I have 2 - 48in shop lights attached to my plant stands with seedlings directly under them. In one of the shop lights the bulbs are Sylvania wide spectrum grolux. In the other are GE wide spectrum plant and aquarium. The Sylvania bulbs are new this year (the whole shop light is new) and they are very bright. The GE bulbs seem dim in comparison. They are the same bulbs that I used 2 years ago, although last year they were not used so they were used a total of 4-5 months.

Sorry, for being so long winded. My question is, are the GE bulbs much dimmer because they were already used? Or is it the type of bulb, or could it possibly be the shop light itself? Should I get new bulbs?


Follow-Up Postings:

RE: Question about my lights

Forgot to mention that both types of bulbs indicate that they are 40watt.

RE: Question about my lights

Both bulbs should appear roughly the same brightness to the naked eye, but this can be deceptive because they both produce a lot of light at wavelengths that the eye isn't very sensitive to. Small differences in peoples eyes can make the bulbs look different.

I still think the bulb really is dimmer. It might be old, but four/five months use shouldn't make it so much dimmer that you really note the difference. Maybe 20% dimmer.

The ballast might be different. Different ballast specs can make a significant difference to the brightness on the same 40W tube. Have you tried swapping the tubes into the other light?

RE: Question about my lights

I think it is the ballast because the dimmer one makes a slight hum and the brighter one does not. The plants don't seem to mind so far but I wonder about when they get bigger. I will probably rotate which plants get the better light so that it's fair - lol


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