Advice needed for LED microgrow

[Slim Picky]

Hi all

I'm a long time lurker of these brilliant forums and am in the planning stages of a micro grow but need some advice from more experienced people about whether it is viable.

Due to the need for major stealthiness of the grow it will be a a PC grow in a fairly small case with the dimensions of 16" by 17" by 8" giving me a total area of 1.25 cubic feet. I aim to grow in soil using lst and other training methods to keep the height down. As far as lighting is concerned I am thinking of using LED's. Firstly to keep heat issues at bay and also because the plant can be closer to the light source with fewer issues. However, despite being no electronics expert rather than buying a light panel of any sort I am thinking of building a light for myself. I have been reading copiously on here and other sites to figure out how this would work and am unsure of what size LED's and what colour wavelengths to use. I know they would need to be a mixture of 625-630nm, possibly 660nm red and also 455nm blues. I am thinking of 3w size per LED for a total of 7 3w LED's giving me a huge total of 21watts of light!

The split would be 5 red, 1 blue and 1 white. What would people recommend as the best split of the 5 red LED's? More 625-630nm wavelength or more 660nm? I would be using a squat autoflowering strain (any suggestions?) and aiming to flower as soon as possible.
Also is there enough blue in there and is the white strictly necessary?

I realise the limitations I'm working with and this will be more of an experiment on the efficacy of LED's in such a small space rather than a grow for huge results.

A couple of years ago I would have laughed at even attempting such a grow but scouring the microgrow forums has been more than inspiring, specifically pinstripes LED grow, which did however, use a professionally produced light source even though it was only 28w total light output.

I would appreciate if some of the more seasoned microgrowers who are familiar with LED's could help answer a few of my main questions please:

1) Is it OK to use the LED's available from the far east through a popular auction site or is it better to source branded chips through somewhere like mouser?

2) Since the different wavelengths use differing voltages/currents would I need individual drivers for them? What would be the best way to drive them all?

3) Should I look at building two seperate lights i.e. one mainly blue for veg and then swap this for mainly red for flowering or incorporate as many wavelengths into the same lamp?

Any and all suggestions welcome

Thanks

 

[hempfield]

Hello Picky,

I think that you will enjoy reading topics on the LED Grow Lights forum, especially the threads related to DIY projects.

On a restricted space like yours I recommend you to use 3W chips from Ebay, which are the most affordable LEDs on the market today.

Keep in mind that RED spectrum makes the plant to stretch, so is better to have those LEDs turned off until the third week of flowering.

You can go for two LED drivers, one only for RED, and one for BLUE and WHITE.

Anyway, for a much simple setup you can use 10W white LEDs ( cool and warm white), in a ratio of 2:1 (WW/CW) for a total power consumption of 30W or 3:2 (WW/CW) for a 50W setup.

For more questions related to this subject do not hesitate to ask on Building a Home Made LED

 

[CouchGrass]

Hi Slim

I just finished up a pc grow under a sodium light but I checked out LED lighting first for the same reasons as you. I decided against them in the end for a couple of reasons.
Firstly those 3 watt units might be a bit too powerful for your cab, the blurb on the commercial units that employ 3w chips suggests using them about 12 inches from the canopy which is no good for us.
Another thing I figured (but I could well be wrong here) is that plants convert light to energy which in turn drives their growth. It made me think that if I use a low total energy then the plants won't have enough to convert into good growth.
I know LED's are using energy targetted at the main frequencies but even so, 21w is only 21w and that isn't a lot of energy for the plants to convert into growth.
The calculations I did suggested that 45x1w would be the target for intensity and coverage; Blue light carries 2.5x the energy of red light so the ratio should be around 3 red to 1 blue; Plants use other spectrums for flavour (carotenoids) so try to cover the carotenoid peak as well as the chlorophyll peaks, can't remember what wavelength that is but the red and blue are 469nm and 667nm.

Just to also point out that there is a scientific effect known as the Emerson Enhancement Effect which seems to explain why sodium can be so effective at growing weed without any additional blue. This uses a combination of 667nm and 740nm which increases the rate of photosynthesis when the 2 wavelengths are used simultaneously. Might pay to cover that as well if you want to max your production.

Maybe 1 other thing to note is that LED technology still has a problem that cannot be overcome and which is called dropoff. Up to now, nobody can find a solution and it means that bigger LED's don't work in the same way smaller LED's do. The upshot is that 3w LED's are in fact 2w LED's and the more power they use, the less efficient they become.

I still my try a LED setup in my case in the future as they do offer a lot for a small grow setup, but to produce a 45x1w unit with at least 4 wavelengths was always going to be much more expensive and less predictable than just slotting a security lamp in there and sorting out the cooling.

Hope that helps.

 

[Slim Picky]

Thanks for the input guys

hempfield - I've been reading quite a few threads on here that discuss LED's and I did see that one too although I may have been skimming cos when I get interested in something I tend to devour lots of info about it at the same time!
I did see your LED panel and it looks really good but you're obviously working with a far bigger space than me. My issue is going to be cooling such a small space whilst remaining stealth.
I agree that the 3w chips are cheap enough to experiment with and I've decided to order a small sample to play around with. I can knock up a worklight to keep in the car if nothing else!
I guess I'm getting so wrapped up in the green and blue wavelengths that I hadn't even thought about using the cool and warm white 10w chips. My only concern with the larger wattages is that from what I've seen the heatsinks get quite big, thus eating into an already small space. What is your experience of how much heat these chips put out? Would it be controllable?

CouchGrass - You make some good points and I can see you're a little way ahead of me on the reading list for this subject. My initial thoughts were to use a 70w hps lamp that I got from somebody but even running that in a box the same size as the case the heat became an issue very quickly. Not very scientific I know but enough to convince me that it wouldn't be viable for me since more cooling equals more noise and less stealth.

If I understand you correctly you're saying that the 1w chips would be most efficient? In this case, you're absolutely right that daisychaining 45 of them would present more problems than solutions. But whilst not ideal what if I could squeeze say 25-30w in there? A combination of say 3, 10 and 1w chips. Do you think that would produce anything, even off a single plant?
Again I allude to pinstripes impressive grow using only 28watts.

I hadn't, however, realised that the lights needed to be at a particular distance from the plants under LED's. I'm assuming this means that whilst heat burning plants wouldnt be an issue, the efficacy of the light would be reduced or be otherwise harmful so close to the plant? Leading to bleaching or somesuch?

If this is true then I guess it puts a kibosh on the whole thing and may be a case of back to the drawing board for this grow idea.

 

[rootidec]

all the best if you're going with leds,
I'd love to build one myself in the future...
but in a pc I would still sit on cfls: terrific value and can be kept at 0 distance from the plant/s.
Also a 70 hps would be killer and give you phat nugz...
No pun intended... just an opinion

 

[CouchGrass]

I sincerely hope you persevere, I was only offering findings as they apply to me in my grow.

Due to the nature of LED lights, 3x1w will always outperform 1x3w. Closer inspection of 3w chips shows that they only draw 2.1w. This is because they do not emit any extra light when run at 3w so the extra current simply converts into heat.
In terms of efficiency and minimal heat then, 1w chips are the way to go.
As for bleaching, take a look at the 1st pic in this thread
http://www.icmag.com/ic/showthread.php?t=225245
It is from a led pc grow.

I can't find the grow you cited but it is worth remembering that there are many variables that need dialling in to achieve maximum results. Temps (both lights on and off), humidity, medium, nutes, ph, genetics and air exchange all need to be ideal. I infer from your post that maybe air exchange needs looking at if you have trouble cooling a 70w hps.
I would also respectfully suggest that pinstripe's grow is the exception and not the rule. There are some pretty disappointing LED setups out there as well once you start to look.

A very cool site for pics and info is ledgrow dot eu, check out the Q&A section especially and look for a post from Igor in Poland about half way down that page.

If it helps at all, I am looking at changing my cooling setup. My thinking is to use a 3 inch bilge blower in 1 corner of my case running from top to bottom. At the top I will attach a 75mm aftermarket cone air filter from a car and the other end will employ a home made fan silencer unit. I plan to exit the air from the bottom of the case. As the bilge blowers use 12v it is easy to reduce power to them and make them more quiet.

 

[Slim Picky]

Hey Couchgrass

No worries. It takes more than that to put me off an idea! I'm just fed up of having to deal with nefarious characters on the street. However, I would only attempt a grow if I knew I could keep it safe and stealth.

I've been off reading a lot more around LED's, specifically how they are used in small spaces and honestly the reading has been encouraging.
My apologies on one point. The reason you couldn't find the grow I kept referring to was because the user who posted the details of it wasn't called pinstripe as I repeatedly mentioned but rather a user called VerdantGreen. But upon checking that thread again I did see that he had more headroom and the lamp was mounted higher than I would be able to maintain it. Sorry for the confusion.

However, looking further back through the microgrow forum I came across a grow diary posted by a user called trem0lo who grew using LED's in a PC case and produced surprising results. His is one of the best put together PC case grows I think I've ever come across and a confirmation of how, once everything is dialled in, how productive LED's can be in a very small space.

So I am still seriously considering LED's in a case, just decided to try and read a lot more before I buy any parts.

Thanks

 

[rootidec]

I remember that thread,
it's also in some link compilation here on Ic, in the led section?
that was really killer, ridicolously low wattage and fair yeld
also, clean crafty setup to look at

 

[BrownThumb]

There are several people on here that are LED wonks and others who seem to know about every type of light. You shouldn't have a problem getting your plan dialed in if you just absorb what is already here for the most part. I am not sure there is a good brand that would make a unit small enough to fit in a PC case, but I haven't looked for anything that small, so don't know. Frankly, I'd skip the LED angle and go w/ nasty old CFL's @ 6500-veg and 2700-flower. Cheaper and easier to install in a tiny space with relatively low heat generation. Less $, less hassle, crappier pizza.