Light Confusion

[420martini]

A lot of people have a lot of opinions on indoor lighting. It always comes down to lumens and it seems like the more lumens you can produce the better your crop is going to produce. I've looked at 4 foot 8 bulb T5's. as well as 400W 600W and 1000W lights in vented hoods. However, a lot of what you read is contradictive. A book says use "this", the sales guy says use "that" and another book says "no you need to do this".

Does anyone know how many lumens a plant can absorb in any given time frame? Do I really need to produce 150,000 lumens (hypothetical) when a plant can only absorb 15 lumens in a given time frame?

Price is not an issue. Common sense is. And for the sake of anyone that can answer this question just assume it's 6 plants in a 4X8 room with reflective walls, cieling, and floors, vemtalation, and ideal humidity.

How many lumens can one plant absorb?

 

[bullisok]

basics of it... The Brighter lights 1000 watt HPS gets better penatration... Deeper in the plant and wider spread. You can use two 600w and get more light coverage you put them side by side and only use a little more electric, but if you have large Bush plants you won't get deep down in the plants and Fruit will be smaller the deaper you go. So you have to decide Larger plants where you need the light to go deep or smaller plants but a lot more over a wider spread area... Remember HEAT too... 1000 watt lights get hot. Better to run 2 600w in a smaller confined area.

 

[TorturedSoul]

Welcome to 420Magazine.

Keep in mind that lumen (and lux) is a measurement that is heavily-weighted towards the portions of the visible spectrum that the human eye perceives as being brightest - NOT what is most useful to plants or even an unweighted absolute. Much of what the eye perceives as being bright is of little or no value to plants. Therefore, lumen numbers really aren't the best indicator in regards to growing cannabis (or other plants) and is best used when comparing lights that are guaranteed to have exactly the same spectral profile.

When lights were mostly of the same type (well, only a few different ones) and bulbs of only a few different color temperatures and spectral profiles, it was considered to be more useful - you could assume (often even be correct in your assumption) that when switching from a 400-watt HPS to a 1000-watt HPS, the spectral profile would remain the same and that the increase in light would be equal across the board.

Now days, not so much. In that I mean... Well, consider two lights - a HPS and an LED panel. If the LED panel is comprised of LEDs that are thought to be most beneficial to plants, it may produce less lumen that the LED (possibly quite a bit less). Even though the LED panel might well produce more gross illumination - and perhaps significantly more illumination/radiation in the ranges that would be most conducive to growing plants.

BtW, should this thread be in the 420 Product Reviews forum?

BtW #2, I noticed that you mentioned the number of plants in your space. That really has no bearing on the question. For one, you might have more plants than the next person but they might have more total plant "matter" due to a longer vegetative period, choice of strain, or several other factors. For another thing... I've never figured out how to get the light to shine all of its light on the plants and not waste any. "Lol," but it's true - figure out the footprint (at a useful distance/height) of whatever light you decide on and its penetrative ability, and size your grow room accordingly & attempt to grow in such a way that you take full advantage of that space and have a depth-of-canopy to match. As someone once said, any light that reaches the floor under your canopy is wasted. To an extent (but less so), the same could be said for light that reaches your walls - even with the best and most reflective surfaces, you're not going to reflect the full 100% of the light that hits them, and even if you did, there's that whole inverse square thing about light's usefulness decreasing over distance (from the light to the wall and then to the plant, in this case). Try for the most reflective surface that you can - because some light will end up hitting the walls regardless - but also try to get as much of it to hit your plants/canopy as is possible. That is affected by your choice of light (not just wattage, but type), distance, and the reflector you use (some do a good job of spreading the light which allows the fixture to be positioned closer to the canopy, some are better at keeping a narrow-focus for better penetration - although you might find yourself raising it in order to try to extend its footprint, lol - and some may not have properly-designed or highly-reflective surfaces or are just sh*t).

Don't let me scare you - in practice it's not that complicated unless you're chasing the absolute most illumination and efficiency possible (although we all should be since it'll cost the same each month to run whether it's in a good reflector, a great one, a poor one - or even no reflector in a vertical setup in the midst of the canopy). I wrote this only to illustrate that the lumen/lux/luminous flux measurement is not as meaningful as most people (including me, half the time) believe in the horticultural world and that regardless of the actual illumination produced by any given bulb/light source, there are other factors in play that are important.

Sorry for rambling.

 

[bullisok]

Tortured Soul you are so right on but to 420Martini The confusion is going to get worse before it gets better because of LED into the equasion now. There is no true regulation and companys are stating facts about their lights that have no true regulations or basis of fact. It's a money maker and now companys are designing and reserching more then ever. I am actually looking forward to when Quality LED prices drop to resonable prices. I love to play with new sorces, but not at the expence of my Wallet. I"m an old soul who keeps it simple, but willing to learn and change.

 

[420martini]

Just wanted to follow up on my earlier post. I went with 600W HPS lights after veging with a 8 bulb T-5 CFL. The heat produced from the HPS light was simply over the top. It was a constant battle right out of the gate and I sort of felt like I was trying to hammer my grow into submission with brute force. So I ordered 3 full spectrum 90W LED'S after doing a lot of research. Wow...my plants are in love with the led's and there is no heat to deal with, not to mention the power savings. I was a little sketched about making the switch at first, but after they were up an running for just a few days it became crystal clear that it was a smart move.

 

[TorturedSoul]

I don't know about the 90-watt LEDS - are they like the UFOs? - but some of the higher-wattage LEDs are pretty fierce. I've been following along with IrishBoy's various grows and have been Suitably Impressed, lol.

His 1080-watt GrowLEDHydro grow:
1080w LED Inferno

His 480-watt GrowLEDHydro grow:
480W & 720W LED Grow - Land of Clovers

The latter is his current grow, which he just started. The former is the one he just finished, but there is still some discussion. It had some interesting developments along the way - he didn't call it the Inferno for nothing, lol.