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Bulb for lighting?

Home Depot has these for around $8 each.

TCP Light Bulb Model 28927
(edited to only show pertinant info)

Light Output: 1,950 lumens
Energy Used: 27 watts
Color: 5,100K
CRI: 84

It says, "Replaces 100W incandescent bulb". So, do I need to get a 100W fixture for this? How many of these would be needed for a 20 gallon Drosera terrarium?
 
No, it means that if you plugged one of these bulbs in to a lamp and 100 watt incandescent into another lamp and put them side-by-side, they would appear to give off the same amount of light to the human eye. Fluorescents use less electricity to put out more light. Compact fluorescent boxes have, "Replaces 100W incandescent bulb" printed on them so that consumers know what kind of brightness to expect - a 100W CF bulb would be staggeringly bright. So, you actually only need a lamp rated for 27 watts for those bulbs. Many growers on the forum seem to recommend the 50 and 65 watt compact fluorescents that some hardware stores carry, but I've found that these work well enough for many plants.
For a 20-gallon tank, I'd use about four, evenly spaced along the length of the terrarium. I'm assuming you have a long tank and not a tall or particularly deep one. What kind of fixtures are you using? It might be just as easy to get some four-foot shoplights - as big as they are, they're actually less expensive than many other types of fixture and bulb because they're so widely used in industry. Almost all of my plants are on four-foot 40 watt fluorescents.
~Joe
 
Well, I just went down to one of our client's warehouses, an electrical contractor. When they re-wire warehouses, they always throw out the old fixtures and install new. He took me to a huge pile of fixtures and said, "Take what you want. Garbage pickup is Wednesday."

They had several 48in, 4 bulb fixtures. They also had some 2ftx2ft box lights that took 4 weird U shaped bulbs. The weird ones are wired for 120 and have to be hard wired in.

I haven't taken anything yet. He said the 48in fixtures had 4 bulbs @ 32 watts in each, but I assume they're easy enough to change out.

I'll take some measurements of my tanks. If they're only 24in, I doubt I'll take them because these fixtures would be much too large. However, if they are of the 30in variety, I think these should do fine. Any thoughts?
 
There is a total of 80W of cool white fluorescent lighting (2 2' long fixtures each with 2 20W tubes) 5" above my plants in a 20gal long terrarium. The remainder of my plants have been moved out of terraria and into 4' L x 2' W grow racks where they sit 5" under 160W lighting (2 4' long fixtures each with 2 40W tubes).

Seedjar is correct, the larger the fixture, the cheaper the price. 2, 3 and 4' fixtures cost ~ 25, 20 and $10, respectively. I'd grab as many fixtures as I could store--who knows how many plants you'll collect in the near future...hehe.

As far as how much lighting you need, you first must tell us the area of your grow space and how far the plants will be from the lights.
 
U-shaped bulbs have nice square fixtures, but are fairly expensive to buy replacements for. However, if they're rated for a 120 line, you can just connect them up to a standard three-prong cord and plug them into your wall (provided you have 120 lines in your home, like most of us do - just don't get a strange plug and put it in your 220 heavy appliance outlet. Come to think of it, read up on home electrical work before doing anything like this.)
I'd go with the four-foot fixtures, and see if you can't figure out what wattage they're rated for. If they're too big now, they won't be much longer, the way most of our collections go. Besides, the excess light on either end of the fixture will still be beneficial to your plants. For the price you would spend on a setup for two foot lights you could buy or build a rack big enough to accommodate those free fixtures.
They may be able to take 40W bulbs; just because they had 32W bulbs it doesn't mean they can't take higher. Many businesses buy 32W bulbs because they are a little cheaper to buy and run, and only a little dimmer to the human eye. You should be able to tell by looking at the ballast (usually a big black box with a very detailed label) which is wired between the light bulbs and the wires running to the wall. The ballast should be labeled with a range of operating tolerances, including the maximum wattage it's designed to put out. Or you can call the manufacturer, or ask your client.
Anyways, you're one lucky guy to have all those fixtures for free. This might be a good time to build yourself a grow rack. I bet you could get a few good trades on the trading forum if you grabbed some extras.
Have fun,
~Joe
 
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