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Old 10-27-2016, 06:22 AM
Psycrops Psycrops is offline
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Join Date: Oct 2016
Posts: 2

Originally Posted by trurl View Post
I have really no idea what I am talking about, but I did just get through setting up homemade leds for my first grow! If you are getting just led bulbs you will need a lot more than just the bulbs themselves. Are you getting panels?

These are LEDs that are used in a T8 fixture. You just rewire the ballast slightly and they work (or so it's said). No panels.

Originally Posted by GpsFrontier View Post
Hello Psycrops,
I would use florescent lights for growing lettuce and kale on small scale. HID (metal halide) lights on large scale. Why? Because it's the most cost effective, and being cost effective is very important to me. You said you plan to have 3 raft systems but you didn't say how many Sq feet it would be. First I wouldn't grow lettuce and kale in the same system since kale needs a stronger nutrient solution than lettuce.

They grow area per raft will be 55"L x 45"W and around 20-25"T of wiggle room for the lights/plants, which works out to 16.25sq ft. Lettuce will occupy the top raft and kale for the other two rafts. Kale also grows taller so it will have more height in that area. I already got the PPM/EC/CF and preferred pH figured out for the different varieties.

The fixture is 48"L x 5.5"W. They will be spaced 7" apart w/ 7" of space @ the end.

If using 1,500 lumens per sq ft, it comes out to 18,300 lumens w/ fluorescents & 13,800 w/ LEDs (24,375 lumens needed). I guess that's how it's measured out.

The numbers don't make since. Seems many sources have different numbers and for the most part, seems like they're being pulled out of someones ass w/ no reasoning behind it. Ive seen grows use much less. If worse comes to worse, I can always use less grow space and tighten fixture gaping.

The interior top/bottom/sides/+raft base will also be wrapped in mylar which should hopefully help with maximizing light.

Originally Posted by GpsFrontier View Post
Manufactures of LED lights like to promote their products as more energy efficient. But in reality you don't save much at all, and if you do manage to save some money in electricity, it will take between 5 and 10 years to break even for the much higher equipment costs. I'm not going to wait that long to start saving.

Two 4 foot twin bulb T5 florescent lights (216 watts) is enough to cover a 2x4 foot space (8 Sq feet), possibly even a 3x4 foot space (12 Sq feet). Or 6 four foot T8 bulbs (192 watts) to cover the same space. Since you will need between 25 and 35 watts of LED lighting per SQ foot, you won't be saving anything. In fact it will probably cost more to run LED lights.

The numbers I ran above show the LEDs to be on par with the fluorescents in terms of costs for the first year, and dropping to around 31% in energy costs the following years. That's not real word though numbers though, just something to go by. Not 100% sure how efficient the brand I'm getting is, as they're from overseas.

If using wattage per sq ft, LED-25w per sq ft would put it @ 406.25w required. The LEDs only total to 132w (22w/6 bulbs). Which means I would need 274w/12 more bulbs ($121.92) and around $90 more in light fixture money.

Originally Posted by GpsFrontier View Post
Even if you can manage to do OK with using just 25 watts per Sq foot of LED lights you would only be saving 16 watts. Using the national average of 10 cents per kilowatt hr, those 16 watts only save you $0.86 cents a month running the lights for 18 hours a day.

The only thing that peaked my interest to the LEDs was being curious if I could get away with using less lumens for my particular situation. Since that particular LED could fit the fixture I was looking at, it was the cheapest of the LEDs and the fluorescent was the cheapest of the fluorescent.

If factoring lumens or wattage per sq foot, then LEDs will never win as you're always going to need to match wattage or lumens regardless of bulb type. The only thing it seems LED has over fluorescent is lumens per wattage and bulb life (quality control issues don't factor in), which my above options put it to around 104 lumen per watt for the LED and 95 lumen per watt for the fluorescent. So @ the end of the day that's not much cost savings to do cartwheels over.

Originally Posted by GpsFrontier View Post
As I said lumins is only useful in comparing similar bulb types. As an example, if you were comparing Metal Halid Bulbs, and a 400 watt MH bulb put out 36,000 lumens, and the 200 watt bulb put out 18,000 lumens, and the 100 watt bulb put out 9,000 lumens, you can see that the lumen output is proportional to the wattage, and you can assume the par output will be proportional as well. In other words four 100 watt bulbs would give you the same lumen/par output as one 400 watt bulb. But since distance from the bulb is important, you could space the 4 lower wattage bulbs out and get better overall coverage from the 4 bulbs than the single higher wattage bulb, and for the same amount of electricity/wattage consumed.

For my particular setup size. I couldn't get away w/ using a MH in my setup as I only will have 20-25"T of room per raft. I should had mentioned this earlier, but the rafts stack on top of each other. The whole setup will be around 59"L x 48"W x 80-90"T and will house 3 rafts.

MH is the best bet, but I wish they made longer bulbs as I have some ground to cover. Plus they're only around $8 which is absolutely nuts.

Thanks for the informative feedback. Maybe I'm over complicating stuff.
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