Aluminum Foil

[Alistair]

Per good advice from some of you folks on this site I stopped using aluminum foil. Some believe that aluminum foil can create hot spots, while others think it's a myth. Ever since I started using HIDs to light my grow space my plants have suffered from heat stress. I consider heat stress to be similar to nutrient burn, inasmuch as the signs are similar. When I refer to heat stress I don't mean burning a leaf because it was too close to the light. I mean nutrient burn-like signs with leaf edges that curl upward.

That being said, this is the first grow in which the plants have suffered no heat stress whatsoever. I did burn a few tops the other day, because the light was too close. However, these top leaves were burnt like someone had taken a magnifying glass, or a match and literally burnt them, not what I consider to be traditional heat stress. We've been experiencing a heat wave where I live, and the closet temperature in the afternoon has consistently been in the 90's for the past week or so. One day the temperature was 102. Although these temperatures are undesirable, the plants are healthy, and nary a sign of heat stress.

This isn't proof that aluminum foil can contribute to heat stress, but there might be a correlation between the two. I removed the foil before starting this grow and painted the walls flat white.

I thought that I'd share this, because I like sharing discoveries new to myself.
I still plan on getting an air conditioning unit though.

 

[da_devil_90]

Sounds good, imo al-foil jus holds in heat, dull side out, its only when you have the shiny side reflecting lights on to the plant, its all a matter of opinion tho as you said. Its always round 38-40 degrees(c) here so I gotta be careful with my ventilation and wat reflective materials I use. Its a sweet 32-35 degrees (c) with no heat stress or burns from al-foil. So it is rly jus a matter of wat works for u imo

 

[BBFan]

102 degrees? Wow that's hot. High heat often results in more males. You got any co2 supplementing that?
Not that I feel bad for you because of your warm weather- it's been below freezing here for over a week! Brrrr.
Good luck.

 

[Hick]

aluminum foil is great stuff...."for the BBQ grill"...
Flat white paint..:aok:
easy to install, easy to clean, easy to resurface, second only to mylar in reflective qualities...

 

[WeedHopper]

If ya wanna roast yer girls,,go right ahead. Foil was never a good reflector of light. It is for cooking. Holds in heat. Mylar is the way to go,,,our Flat White Paint. And yes,, I used foil in my younger days.

 

[Rockster]

'Hot spots' do not exist within a growroom and are certainly not caused by ali foil.

Heat can travel by means of three ways,conduction,which is heat passing through a material.

If you heat a piece of copper held in your hand the heat conducts along its length and you drop it as it becomes hot.

Radiation,which is the warmth you feel from the heat energy directly radiated from the lamp and requires no medium to carry it.

And convection,which is heat being transferred from place to place within a body of air or other gas.

Radiation cannot 'collect' in an area so that can't cause hot spots.It heats the ali foil but the foil has little mass so what is absorbed is conducted away by what its mounted on be it a wall or panel board of a cupboard etc.

Conduction cannot cause hot spots as ali foil doesnt conduct a lot of heat as there isnt much mass to it.

Convection or rather poor convection from too little vent can cause hot air to stratify in a layer at the top of the growroom and is the closest thing to a 'hot spot' in a grow.

Also,poor reflectors make hot spots of a kind as there is a concentration of heat and light energy usually directly beneath it which is why diffusers are used which are designed to be situated right in that 'hot spot'.

So the ali foil thing is a grow myth I'm afraid.It's not the best reflective material to use but is quite adequate and does not cause stretching due to these mythical zones called hot spots.

 

[The Hemp Goddess]

And yes,, I used foil in my younger days.

LOL--A lot of us did--we didn't have forums like this telling us it was bad. But, yeah, just because a material looks like it reflects, doesn't mean it does...mirrors fall into the same category.

 

[Rockster]

It's not bad in anyway Hemp Goddess,it's just not as efficient a reflector as other materials.

 

[Alistair]

BBfan, no I don't have CO2 supplementation. In order for the grow room to benefit from that, the door would have to be closed. The door is kept open at all times when the lights are on.

Rockster,

That's a well thought out post. Perhaps you're right, I don't know. There is also another difference in my closet I over-looked: I do have better ventilation cooling the HID, and that would make sense with what you said concerning convection and the reflector. However, there are no cool tubes, etc., and the ventilation is simple and primitive.

So, perhaps I jumped to conclusions. It was just an idea, and correlation isn't necessarily causation. Thanks, for the post.

 

[pcduck]

'Hot spots' do not exist within a growroom .....

:rofl: imperfections in your bulb will cause hot spots. just like a magnifying glass. Just my $0.02

 

[Rockster]

:rofl: imperfections in your bulb will cause hot spots. just like a magnifying glass. Just my $0.02

I'm sorry but that just isnt so pcduck,as a slight imperfection in the glass,even if it were lens shaped(which requires a change in thickness of the glass) could only focus to within centimeters of the glass itself but this doesnt happen anyway.

So lets keep it real huh?

 

[pcduck]

So lets keep it real huh?

I am using past experience. What are you using? If you want to keep it real.

 

[Rockster]

I am using past experience. What are you using? If you want to keep it real.

So you had a bulb that focused rays into a hot spot over and above the radiation diffused by the whole lamp?

I'm sorry,you are contradicting the known laws of physics pcduck.

How big was this imperfection on the lamp?

I could put a proper magnifying glass right next to a lamp and it would do nothing apart from focus on a point a few cm away and then diffuse again into the rest of the room.

Stop being a contrary Mary!

 

[pcduck]

I guess we will just have to agree to disagree.... Since you will never change my mind on this..... And as far as being a contrary Mary I would check out your own posts first.

 

[84VW]

It's not bad in anyway Hemp Goddess,it's just not as efficient a reflector as other materials.

well, since aluminum foil does not reflect as good as mylar or even a flat white paint i would say its not good

its harder to handle and use than mylar or a flat white paint which is not good

and it is made for cooking and made to hold in heat....hmm, i would say it does what its made to do

you really cant clean it, just take it down and replace with more tricky to handle and hang alu foil which is not good

these are a few things that are not good and i would consider BAD

but hey, this is just my opinion,

 

[Rockster]

Care to elaborate pcduck as I don't see where I have contradicted myself but if I have would really like to be made aware of it?

Shame I can't change you mind with reason,logic and physics but there ya go,you can't say I did'nt try?

Peace brother.

 

[pcduck]

I still have the lamp. Just send me $72.00 and your address and you can have it...Dude you need to read some of the you stuff have written. Either 80 to 100% of the people are wrong or you are the smartest person on the internet..

Example: ph is not important.... remember that one

 

[Alistair]

One thing I do recall concerning tin foil and cooking: It doesn't retain heat. I grab right hold of it seconds after having removed it from the oven without getting burned.

 

[Rockster]

Oh dear,seems you want to shoot me down somehow and I thought we were all on the same team?

I didn't say ph is not important but I said too much is made of it as if you have a good compost sorted,know your tap and feed ph,mine being 7.3,I don't need to ph down as I know the compost will knock it back into the correct range and this is reflected in my yields of 500 gsm+.

I used to ph down a bit but don't bother anymore and my yields have not changed so for me personally for my grow "its not that important",ok?

For others who make custom composts and add feed various stuff,like bone meal,bat guano,kelp extract etc,well then it will be of more importance.

I apologise for maybe not writing what I did in the clearest and most concise manner which it seems made you think I thought ph is of NO importance and of course that isnt so.

Peace.

 

[HippyInEngland]

I had a hps and the end of the bulb was not smooth and perfectly round, it had like a blob at the end of it, it did cause a focal point about 2ft out from the end of the bulb, didnt cause me a problem when a reflector was added.