WPG queastion (Setting up a tank today)

[D'cecilia]

I bought 4 Florescent Daylight 6500k 100/23 Watt bulbs yesterday.
They are equal to a 100W bulb, but only use 23? How many
Watts per gallon would I actually get if I use all 4? or just 3?
I make my own "fixtures" and they have worked well before, but
want to know for how many bulbs i should make it.
I want to run a "mid" tech tank? Haha.
Mostly want to plant Rotalas, hygros, some Hairgrass
maybe, Vals, bacopa's.
Would those bulbs be enough? Or maybe too much?
I am going to use a 20L.

Thanks in advance.

[Steve001]

Originally Posted by D'cecilia

I bought 4 Florescent Daylight 6500k 100/23 Watt bulbs yesterday.
They are equal to a 100W bulb, but only use 23? How many
Watts per gallon would I actually get if I use all 4? or just 3?
I make my own "fixtures" and they have worked well before, but
want to know for how many bulbs i should make it.
I want to run a "mid" tech tank? Haha.
Mostly want to plant Rotalas, hygros, some Hairgrass
maybe, Vals, bacopa's.
Would those bulbs be enough? Or maybe too much?
I am going to use a 20L.

Thanks in advance.

4x23=92 W
3x23=69 W
respectively

That's how many watts you'd get. As you can see that doesn't really tell you much because watts is a measure of how much electrical energy will used in 1 hour by these bulbs. It's a very inaccurate way of determining how much visible light is actually generated. These lights also generate waste heat which is another form of light. Also, it does not answer how high the PAR ( photosynthetically Active Radiation ) values are or the overall Lux of these bulbs.
There's two very good stickies at the top of this sub-forum page that could probably answers all or most of your questions or at the least give a better idea of what is needed to be known.

[Hoppy]

One more time: watts per gallon is a meaningless number. The amount of light (PAR) you will get from those bulbs depends on whether you mount them horizontal or vertical above the tank, and what you use for reflectors. See the sticky for more details.

You don't mention CO2. That is at least as important as light in determining how well this will work.

Edit: Ninja'd

[D'cecilia]

Thank you both for your responses. I will deffenetly check out those sticky's.
And yeah I never really understood lighting when it came to planted tanks.
I just knew that you needed at least 6500k for the plants to actually take
it in.

I had a 5 gallon tank with two of these bulbs, smaller ones, i think 13w. I
used dry fertilizers, DIY Co2, and the tank was really green and the plants
did awsome. That's what I plan to do with this one, just in a bigger scale.

I am also using Eco-complete as substrate, and a Cascade 150.

[D'cecilia]

What could I use as a reflector?

[Hoppy]

A 20 long tank is only 12 inches high. If the lights sit on the top of the tank they are very close to the substrate, so the light intensity is pretty high with 13-14 watt spiral screw-in CFL bulbs, even if they are horizontal - at least high for not using CO2. One way to make a light, with reflectors, for those bulbs is http://www.plantedtank.net/forums/di...g-planted.html For a 30 inch long tank you would need 3 bulbs spaced over the length to get reasonably uniform light.