What wattage and lumen to use?

[Synthtcd]

That does sound perfect, where did you find the fixture? Also at Home Depot? Is it the sort that's meant to be bolted to the ceiling? Do you know off hand how much the fixture/bulbs cost you?

[Studdlygoof]

Does Home Depot carry Compact Floresent (CF) fitures? I've only seen them cary regular Floresent fixtures that take the T5 - T8 bulbs....i'm going to have to check into that

[Synthtcd]

When I look on ebay for compact fluorescents I see several people going on about CF having more wattage than incandescent. For example one auction claims:

"They are 23 watts but are equivalent to 120 watts of incandescent light wattage."

"This unit's bulbs are rated to makes 3600 real lumens, about as much light as a "65 watt (=500 watt, 8000 phony lumen) fluorex"

Should I give any attention to these claims or are they just ranting about their product?

[salvoz]

I would typically disregard the "equivalent to" language regarding the wattage comparisons, although incandescent lights are indeed very inefficient in their light output and generate tons of unwated heat. For a general artificial lighting rule a thumb in the hydroponic growing world, you can grow most plants/veggies by using a minimum of 40 watts of HID or flourescent lighting per square foot. But this is probably overkill for most vivs...unless they are very tall or the plants are light-needy. Maybe shoot for 30 watts per square foot of viv floorspace and watch the plants for signs of either too much or too little light and adjust accordingly...just watch your temps!

[defaced]

These are sold in the area for outdoor lighting. They are intended to be bolted to a conduit box, but you don't have to. DartMan made a thread a few weeks ago on how people mounted theirs.

The 65w fixtures are 40 dollars each and replacement bulbs are between 10 and 15 bucks. When you buy the fixture you get a bulb and all of the wiring hardware. The only thing you have to do is wire it to either a box or a cord.

[Studdlygoof]

Originally Posted by salvoz

...you can grow most plants/veggies by using a minimum of 40 watts of HID or flourescent lighting per square foot...

...shoot for 30 watts per square foot of viv floorspace...

Salvoz - I think you have some useful information but i'm a little confused on your formulas...

Your first statement makes it sound like we should do calculation by square feet of the ENTIRE tank (as in the total volume)

The second statment makes it sound like we should calculate wattage according to the square foot of viv floorspace (...which would be area...)

Defaced - Thanks for that info....never thought to check in outdoor lighting...now are the CF bulbs used for those the straight tubes or the spiral syle?...I have heard that with the spiral style you actual loose more lighting because of the design of the bulb (designed to spread light in every direction instead of a focused area as with straight tube CF)

[salvoz]

Sorry if there was any confusion. But volume is measured in cubic feet, not square feet, technically. For example, when someone says they have a 600 square foot apartment, it is understood that they are not referring to the volume of that appartment, merely the length and width of its floorspace, i.e., its area. Either way, I was definitely referring to floor space, measured by length and width. I would offer no guidelines as to watts per cubic foot of vivarium--that would really be treacherous!

[defaced]

These are shaped like a spiral CF, but each tube is straight. You'll understand when you see them.

Power/area is a poor way to characterize light being put into viv. Power consumed doesn't factor in the efficiency of the bulb which varies greatly for each kind of bulb. Area doesn't take into account the distance the bulb is from the floor of the tank - this is different than volume because we are interested in light flux which is a surface characteristic. For example, I may have a 3000 lumens over 1 sqft at the source, but as I move from the source, say 1ft, I'll only have 1500 lumens/sqft, then at 2ft I only have 750 lumens/sqft. Because of this fall off rate light is not an easy thing to create an accurate rule of thumb for.

[salvoz]

Agreed that watts per square foot is a poor measure, its just a point of reference. i never said it was accurate! Of course, considering all the variables involved, and we can go on all day about those, no rule of thumb here can be accurate. That said, if you are using a tank less than two feet tall, and don't have a light meter, and don't know the lumens required by each of your plants, and all the other factors involved, its as good a starting point as any...

[Studdlygoof]

Good stuff guys...no worries...i won't hold anyone to their formulas...just trying to build an understanding of the entire concept...i do agree that i need to invest in a good light meter because that would be the definate way to tell if i have enough light or not...mucho gracias