Aquaponics As a Food Source

[hollohas]

Just got a call about this thread, and it reminded me to come in here and ask about using LED lights as grow lights. I know they make LED fish tanks now, but can you use LED lights as grow lights? I know nothing about what makes grow lights different from fish, reptile, or other florescent lights, but I know LEDs cost less to run. Anyone have any ideas?

Irving - You will pay A LOT to buy LED fixtures that produce the same amount of light (lumens) as equivalent fluorescent or HID fixtures. The reason most mainstream LED fixtures these days cost less to run is because they are actually giving you less light. Only the most expensive LED fixtures are as efficacious (lumens/watt) as fluorescent fixtures when you need a lot of light. It's easy and cheap to buy a single LED lamp (bulb) that has the same lumens per watt as a fluorescent lamp but you will need lots and lots of them to get the amount of light you need to grow efficiently. If you want a single LED fixture that produces the same amount as a $20, 2-lamp T8 fluorescent shop light (around 6,000 lumens), you will need at the very least a 60 watt LED fixture. And only the very best and most expensive 60 watt LED fixtures will be efficacious enough to produce 6,000/lumens (or in other words, produce 100 lumens per watt). Try to Google a 60W LED fixture that produces 100 lumens per watt. You will be surprised at what you find. It won't be $20. And don't be confused by 60 watt equivalent LED lamps. That's just telling you it's about the same amount of light as a 60W incandescent and will typically only be about 13 watts and give you 600-800 lumens rather than the 6,000 I used in my comparison.

But if you do buy LED fixtures, only buy models that specify not only the wattage, but the lumen output as well. All LED fixtures/lamps will say the wattage. That means NOTHING. You are concerned with lumens.

The other aspect of LED lighting is that only the most expensive fixtures will be full spectrum. Most of the cheap varieties will be highly favored on the blue side of the spectrum because the blue phosphors are the cheapest and most efficacious. Most plants need full spectrum lighting because that's what they get from mother nature. Many expensive LED grow lights have an adjustable spectrum to allow the grower to custom tailor the light color to best match the plant's changing needs during it's life but IMO that's simply not necessary for the home veggie grower.

To get the best use out of any indoor grow lighting it needs to be very close to the plants. I mean inches above them. Most garden veggies require "full sun". That applies to not only time but also amount. The amount of light falling on a surface is measured in foot-candles. Outdoor, mid-day, non-overcast sun in our region measures 10,000+ foot-candles. To give you a comparison, a 4ft, 2-lamp fluorescent 32watt T8 shop light measures around 500 fc 4 inches below the fixture. 12 inches below the fixture it measures around 200 fc. So you can see, for your indoor veggies to thrive in conditions most like mother nature intended, get those lights as close to the plants as possible to benefit from the increased foot-candle level. I made that mistake a few years ago. My lights were mounted too high and my plants grew skinny and tall as they reached for the light. Now I put my lights on an adjustable chain so I can keep them only inches above the plants even as they grow. Now they grow thick and strong. You do not have to worry about over-heating your veggies with fluorescent lighting mounted almost touching the plants. Sometimes I get lazy and don't move my lights. I have had plants in direct contact with my T8 fluorescent fixtures for days on end without any negative effects.

I personally use a combination of different color temperature lamps in my grow lights. I use a mixture of 6500k and 3500k fluorescent lamps to make sure I am covering the spectrum. These are marketed in a variety of names but generally are something like "daylight white" and "warm white" respectively.