The light intensity produced by a LED light, with LEDs spread out over the top of the tank, drops roughly proportional to the distance between the light and the substrate. Once the light is about as far from the substrate as its length, the intensity transitions to dropping with the square of that distance.
Ok, thanks Hoppy! I had asked a question on the San Antonio Aquatic Plant club Facebook page, regarding how much extra light I need to plan for if I want to suspend an LED fixture over my 20L instead of having it rest on the tank. Some have said that the fixture may produce too much light for such a shallow tank, so I may raise it up a few inches, and thought I would see if there is any formula for how much the light diminishes per inch raised. If you know of any article on that topic, please send me a link; but otherwise, thanks and have a great week! Neat drawer slide apparatus, by the way.
Hi Hoppy; someone recommended that I read your post about suspending lighting over a planted tank, but I can't seem to find your previous post on that topic. Any chance you can give me a link? I'm trying to study up for my first planted tank (just a 20L). Thanks so much!
I had an idea for a fish parody, but I'm not skilled enough do it right, so
I invite you to take over. We do things to encourage fish to spawn and reproduce, as if we really know what turns them on. Make a guide that a superior species would come up with if they were trying to get their pet humans to mate and raise their young in captivity.... 'Provide many suitable males, who will complete.. removing all but the one that was selected. .. mating usually occurs at night. .. allow the parents to raise their young. ..' there are a lot of little details that could be added ad far as setting the mood, feeding before lights out,etc. Please message me if you ever take this on. Thanks
If you use some thin aluminum sheet metal, like roof flashing material, and make a reflector which has a cross section like \_/, with the bulb in the middle, so you can see a good reflection of the whole bulb on each side of the actual bulb, you get double the PAR from the bulb compared to having no reflector. Really good, well designed, highly polished reflectors can give about 3 times the PAR of a bare bulb, so the simple reflector made this way is pretty good. I don't think a circular shaped "trough" reflector would work nearly as well.
I found what looks to be a cheap DIY way to light my 20 gallon longs with what I hope to be medium to high light. It involves placing XYZ bulbs in the top of a metal duct shaped into a semicircle. see link below. I can't find any specific info on the reflectivity of that shape or how to determine how far from the apex of the circle to place the bulb for optimum light dispersion. Thinking about it, it seems like a parabolic shape would be better, as well as a reflective triangular shape running the length of the duct the width of the bulb to prevent strikeback. I know there are a more factors than you probably care to address individually, but if you know of an application or website to point me in the right direction, it would be appreciated. Or you could build the reflector yourself, test it with your par meter and give me the specs. juuust kiddingg... kinda. :-) any feedback is appreciated. thank you. http://www.youtube.com/watch?v=Xy5fzPlsXK0
I don't recall ever seeing 40 watt screw-in CFL bulbs. If I had seen them, and they were 6500K bulbs, I would have bought one to play around with. One problem: the dome type reflectors from Home Depot aren't big enough for a bulb much bigger than 26 watt, and even those extend beyond the rim of the reflectors. This makes it harder to use the bigger bulbs, unless they are also the miniature type.