Ok, well either way it seems I'm going with a 48W unit (haven't decided which yet, but I'll worry about that later).
Next step is how to position it.
Unfortunately I don't have any type of light measuring device (or even know where I can find one; no friends in the physics department unfortunately
)
The inverse square law would seem to give me a very (very) rough estimate, but I suppose that's the best place to start.
Going through the numbers, though, I think I'm doing something wrong.
law states: I1/I2 = (D2/D1)^2 (where I is intensity and D is distance)
Let's say I have 48W. Adjusting for the fact that this is T5HO, I get a wattage of 58.56W (multiply 48 * 1.22; source:
Comparison of Lighting Types (Lumens and Watts))
My first round of calculations is considering that normally the light fixture would be positioned about 1/2inch above the water, since trying to use this equation on a medium other than air is probably just going to add more error. I'm going to say that I want a final wattage of 30W. So:
58.56/30 = (D2/0.5)^2
D2 = 0.699in
Meaning I would need to raise the light a total of 0.199in
That can't be right, right? So I redid the calculations considering distance from the light to the substrate (which introduces the issue that water isn't air, but whatever).
This time, D1 = 11in
So D2 = 15.368in
Meaning I would need to raise the light 4.368in
That seems more reasonable, but tbh that's only due to my preconceived notions that I'm putting a ton of light over the tank so that's going to require so large adjustments on my pat.
So.....what am I doing wrong? lol