How to determine lighting for supplemental lighting in my greenhouse (LED) at night

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I'd like to add supplemental lighting to my greenhouse. Currently I am using a string of contractor LED's at night just to trick the plants in order to keep them from flowering. Any idea how to figure out exactly what I need? My last grow averaged 4.8 oz per 30 plants, planted as clones and vegged for 30 days before turning the night lights off. This time I have vegged for 60 days, but due to the slightly shorter day (Hawaii) even with an extra month of veg time, they aren't that much larger than the previous grow. So this brings me to supplemental lighting to extend the "daylight" hours for growth (as opposed to just keeping the plants from flowering like I've been doing). I run 30 plants in 25 gallon grow bags in a 24X48X14 greenhouse. How do I determine wattage, spacing, hanging height, and number of lights? I can't seem to find an answer, believe me, I have read and read, so I'm hoping someone might be able to point me in the right direction. I figure since we get about 12 hours of daylight in the winter, and and the longest day is about 13.5 on June 21... the lights will be on long enough to provide lighting during the dark hours hours which will range somewhere between 6-8 hours per day.
 
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do you want it right =$$$$

or just add 2 more runs of what you have......
That is part of my problem, I'd like to get the growth because this round, I just haven't seen it at all. I suppose it doesn't help if my greenhouse is shaded until 11 AM or so too, but there isn't anything I can do about it. We've only had one or two partly cloudy day in the past 3 weeks, the rest has been overcast and rainy... this is why I'd like to slap some lights in just to get some growth. I know it will cost some, but I think one good harvest would pay for it. I was looking on Alibaba at greenhous LED lighting and it appears I can get 650-1000 watt LED's with decent PAR ratings between $500-600 each, about half of the going rate on the mainland. I just don't know how how many I'd need for a 24X48 area... that will be what determines whether or not I'd move forward with it at all (it all boils down to price). As it is without lighting I'll probably pull at least 10 lbs every 4 months.
 
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i would be looking there also......... best bang for the $$$$$ I was thinking QB but your thinking right on ..>>>>>>>>>>>>>>>
 
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I Grow in Hawaii too! I found these cheep Chinese LEDs to get going kingled.com I will eventually upgrade but the 1000w and up seem to do the trick for a 5'x5' area. they also have them all the way up to 3000w and fairly affordable. I've used them for indoor veg I'm about to do a run in my greenhouse with them to help with veg, ill let you know how it goes.... I have a 10x20 greenhouse and hoping to run 3-4 1000w leds to cover the whole canopy... hope that helps just keep experimenting, I've seen some people just use shop lights and or fluorescents. there's even a trick to just break up the sleep cycle and have your lights come on for at least 3 hours in the middle of the night. as long as you interrupt the sleep cycle they will stay in veg.... so I've been told. experimenting with that myself! hoping to grow trees since here in Hawaii we can only grow 10 plants...
 
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