Grow lights, heaters etc, on a budget

Looks great Loli. 22 degrees - ooooh..
Who wouldn't want to be a seedling in there..

 

@Lolimac those lights (LED right?) need to be just an inch, 2" at most, from the top of the plants

If some plants are shorter then stand their pots on something to raise them so their leaves are only just below the lights.

If the lights are something else (i.e. hot) then choose a distance where the back of your hand doesn't get hot even after 30 seconds

 

@Kristen ...Yes LED.... I'm going to adjust the light tomorrow can't do it now because my finger is still throbbing

 

It doesn't matter quite so much with these ones, because the the beam from each individual LED is very, very focused. Mine is about 8 inches above the tray.

Because the LEDs in the array have gaps between, if you take it too close, you'll end up with some seedlings getting no light at all as they'll be in the gaps between the beams.

 

Good point. The power of the light falls off with the inverse square rule though, so you want them as close as you can possibly get them - without there being heat damage (not a problem with LEDs of course) and, as you say, where the light pattern is even.

 

I don't think the guys on the cannabis forums use foil @fc they use a type of Mylar = something about reflection. In saying that, it might be that foil is OK for our purpose just no good for cannabis ?

S.

 

I used to use kitchen foil for reflectors (e.g. for seedlings on the windowsill to give them some reflected light from the "room side") until I read that it wasn't as good a reflector as you might imagine, and that flat white paint is better, as is Polystyrene sheet too. Mylar is only a few percentage points better, so if you are growing a very high value crop I'm sure its worth it, otherwise spend your money on something else.

 

talking about things white, if you dont have time to repaint or buy polystyrene. White sheets of printing paper will do. Just stick it around your growing area using tape.

 

I'm sceptical about the reasons behind the white vs shiny thing.

I have no doubt that white surfaces are better in most circumstances, but I also think that shiny surfaces reflect more light. Proof of this is when someone leaves something shiny on my colleague's desk at a certain time of morning, when for about 5 minutes, I suddenly get blinded (if its sunny). That doesn't happen if someone leaves a piece of paper on his desk instead.

But I think that's the issue. A good shiny surface like foil will reflect light without diffusing it, so in the growbox for example, light comes from the top, hits the foil at the sides, then bounces off at a similar (but opposite if you know what I mean) angle, missing the plants. Whereas a white surface will scatter the light, so that less of it bounces and misses.

If white was better than shiny, car headlights would have white lining.

 

white is for general brightness as you rightly pointed out it diffuses light.. however, shiny reflects it and in things like car lights it focuses the light in one direction to make it more brighter. However, kitchen foil in propagator will very much work like white paint as it will not be focusing light at any point just generally reflecting it. I prefer white (paper) because when i put foil, it crumples, making things even more chaotic..

 

I thought Mylar was relatively inexpensive, had read that it (especially diamond pattern) was better than both white and foil sheets and as I have about £125 worth of lights in each of my two grow boxes I used it in both of them. It's only £2/m² http://www.3ch.co.uk/accessories/reflective-sheeting/diamond-sheeting-per-metre/prod_1511.html and I used about 2 m² on each box (white polythene was used for covering the bases), so say £5 each allowing for wastage.

 

I don't have a link to anything scientific, and peer reviewed, but this link I found interesting.

WARNING: This link is to a cannabis growing site

http://www.420magazine.com/forums/h...lective-materials-can-i-use-my-grow-room.html

Summary:

• Mylar 92-97%
• Flat white paint 75-85% "does not create hotspots."
• Polystyrene Foam Sheeting (Styrofoam) 75-85%
• Glossy and eggshell whites not reflect light as efficiently as flat white 55-60%
• Aluminium foil is no more than 55% reflective - "if used, make sure that the dull side is the one that is used to reflect the light. When it becomes creased its reflectivity is even lower (around 35%.) It is also very dangerous to use because it creates hotspots easily, is electrically conductive, and is a fire hazard when it is in close contact with HID lighting. Attaching this to walls is a pain and usually using aluminium tape or glue is the best way. This should only be used as a last resort, and even then its usefulness is questionable."

I don't know why aluminium foil is not regarded as a better reflector, as it seems counter intuitive to me.

Other point made in that article, which can be overlooked, is to get the sides as close in as possible - the further the light has to travel side ways, before being reflected and then having to travel all the way back, is losing power (by the inverse square law again)