I'm interested to know if sufficient light is being delivered to my 20 Gallon Tall Tank using an LED Strip Light. I am interested in technical analysis of how well the LEDs are working in comparison to some of the more efficient LED commercial lighting that's out there. I have Ludwigia Repens, Java Fern, Jova Moss, Anubius, and Dwarf Hair Grass in the tank, and my goal is to be able to deliver sufficient light for plants requiring low to medium levels of light. I usually run the light full intensity on COOL WHITE (6500K), and full intensity on RED light, simultaneously.
I got this idea from You Tube, but in the You Tube Video, the inventor used only one strip of SMD5050 strip lighting, designed solely for optics and not applicable for nourishing plants in the aquarium. I wanted to try making one of these strip lights
that would be applicable to a planted tank.
The You Tube project used a piece of plastic house guttering with end caps, and the light strip
was stuck to the inside of the guttering. Most LED strip
lights come in 16.5 foot lengths, and they have double stick tape already afixed to the bottom of the strip. However, while this may have been what was used in the You Tube video, the double stick tape isn't sufficient to reliably permanently afix the strips to the inside of the guttering. I used hot glue to afix the strips to my guttering. I also used metal guttering and end caps because the complete assembly of my strip light fixture
generates some heat, all be it quite moderate. In the case of my fixture, the housing can be touched without any discomfort, and is really only luke warm at the most. I suspect that a plastic housing would be perfectly fine, but I wanted to error on the side of caution, and chose to use metal guttering. I wanted to make a light fixture that would work with plants that have low to medium lighting requirements, java fern, java moss, pennywort, ludwigia repens, dwarf hair grass, etc...
I used a series of 8 strips of 10mm SMD5050 RGB/Warm White + Cool White LEDs inside the gutter housing. The entire strip was rated by the supplier at 72 Watts total. There are 300 LEDS total in a 16.5 foot length of strip lighting, and I used all but about 8" of the complete 16.5 foot strip in my fixture, about 12 LEDs less than was in the complete 16.5 foot strip.
Each of the 8 strips in my fixture contains 18 RGB+Warm White LEDs, and 18 Cool White 6500K LEDs, a total of 144 Red/Green/Blue + Warm White 3000K Leds, and 144 Cool White 6500K LEDs. The individual LED output is rated at .24 Watts per LED (72 watts in the complete strip), so theoretically my fixture will produce .24 watts per LED x 288 LEDs = 69.12 Watts. An entire 16.5 foot strip produces around 2000 Lumens. So, with my light strip
having (12) LEDs less than what is in a 16.5 foot strip, my light fixture is producing a total of around 1920 Lumens at full intensity, not including any natural losses that occur.
Of course, there are losses, both in wattage and lumens, delivered to the tank. I realize that the proper way to measure acceptable levels of light are to measure PAR/PUR values of light that are actually being delivered to the top of the substrate in the tank. I don't have a meter to measure PAR/PUR, so I had to rely upon the manufacturer's specifications in order to get close to the historically accepted method of measuring the proper amount of lighting in watts per gallon delivered to a planted tank. My fixture is intended to be used in a 20 gallon planted tank. So, theoretically, my strip light
is delivering around 3.5 watts per gallon, which is adequate for a planted tank, for plants that require low to medium levels of light.
With regard to the color temperature of light being delivered to my tank, the Cool White LEDs in the strip are rated at 6500K, and there are (144) LEDs, delivering approximately 34.5 watts (minus whatever natural losses occur). There are (144) RGBW lights in the fixture, and at full intensity, the colored LEDs deliver less wattage than the Cool White LEDs. But, when they are on simulataneously, the produce significant amounts of wattage to a 20 gallon tank.
The color temperature of the RGB LEDs is as follows, according to the strip light
Red = 620-630nm
Blue = 460-475nm
Green = 515-530nm
I've been leaving the RED LEDs on at full intensity, along with the Cool White LEDs, to supplement the Cool White (6500K) LEDs in order to deliver the best combination of light to the tank. The Cool White (6500K) LEDs deliver slightly less than what is optimum for the plants with respect to the "RED" range of color temperature. Using the RED LEDs at full intensity should help to supplement what might be lacking with respect to the RED color temperature levels that the plants desire.
Light Fixture on top of the tank...I spray painted the inside of the gutter with white spray paint, to act as a better reflector. I epoxied the ends to the gutter, and also caulked the joints between the gutter ends and the gutter itself. I dremeled a hole in the end of one of the gutter ends so I could bring the wire
out from the light strips to the IR receiver, then caulked the hole where the wire comes through the metal housing in order to protect the wire passing through the gutter end cap from abrasion.
Cool White (6500K) LED/RED LEDs On at Full Intensity
Cool White (6500K) LED/Blue LEDs
on at Full Intensity
Cool Whhite (6500K) LED/Green LEDs on at Full Intensity
Warm White (3000K)/Cool White (6500K) Cool White LEDs on at Full Intensity
All of my technical conclusions as to the proper amount of light being delivered to the tank by this fixture are theoretical, as I am a novice, and just began to research this issue of plant lighting in the relatively recent past. If anyone can validate, or refute, my conclusions, then I welcome the critique, as I would rather know a more valid way in which to judge the quality of light being delivered to the tank than not, and to understand the technicalities more accurately.
If anyone is interested, I have a rather lengthy tutorial prepared that I would be glad to post, assuming that this light is sufficient for nourishing plants, and in case someone would like a few hints on building one. They are pretty cheap to build, about $45.00, versus the cost of my Current Marine LED commercially produced fixture, which was about $130.00. Admittedly, the commercially produced Current Marine LED fixture is superior with respect to bells and whistles, and probably with respect to efficiency, but this alternative may be a good option if your budget is an issue. And, even if this home build is only sufficient for visual lighting in the tank, it is very economical.