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how many watts per Sq foot

overbudjet

Active member
Veteran
I run mine (600watter's) around 8 inch over canope air cooled hood
4 of them over 4'x9'give me around 65 watt per sqft.
 
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TribalSeeds

I run mine (600watter's) around 8 inch over canope air cooled hood
4 of them over 4'x9'give me around 65 watt per sqft.

For whatever reason I cant ever get that close. I had my 600's at about 12" and my leaves were so bleached it was scarey! I did notice it wasnt much of a problem when I was overfeeding the plants though. Perhaps they need more food when they lights are so close?
 

DrFever

Active member
Veteran
You have 40wpsqft... approximately. With reflective surfaces on each side you would get a higher yield... but essentially you're at 40wpsqft. Just fine for more indica dominant strains. :D

Stay Safe! :blowbubbles:

that's what i am saying sure i am getting 40 watts per Sq foot an there are many running more watts per but when i see there harvests or bud shots well you be the judge :) :huggg: bud is on 5 gallon / 20 liter pail
 

DrFever

Active member
Veteran
For whatever reason I cant ever get that close. I had my 600's at about 12" and my leaves were so bleached it was scarey! I did notice it wasnt much of a problem when I was overfeeding the plants though. Perhaps they need more food when they lights are so close?
Tribal best way to determine height of light to top of your plants is place your hand over top of plant if your hand gets to hot then raise light cause if your hand is to hot its to hot for plant :tiphat:
That's why i like 1000's they got penetration power but also there is no need to have it below 24" from tops as 0 - 24 " you lose nothing as per lumens 600's further you place them away from plants more lumens deteriorate quicker
 
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TribalSeeds

My room is cooled by a mini split. I can touch the glass all night long and not feel it get hot at all. Its the intensity that bleached my tops. Theres no heat stress or anything.
 

944s2

Well-known member
ICMag Donor
Veteran
Tribal best way to determine height of light to top of your plants is place your hand over top of plant if your hand gets to hot then raise light cause if your hand is to hot its to hot for plant :tiphat:
That's why i like 1000's they got penetration power but also there is no need to have it below 24" from tops as 0 - 24 " you lose nothing as per lumens 600's further you place them away from plants more lumens deteriorate quicker
hiya,,oldies are goldies dr f,cant beat the" hand under the reflector" but as a rule of thumb for me, most strains i find 14-18in from the tops will usually be ok, i would imagine thats strain dependant though as i have had the odd few where i had to raise lamp higher then 18in but a long time ago and cant remember the strains, i use 3-4 600w,,peace s2
 
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guy fawkes

Active member
Veteran
my room is 4ft x6x 3 = 72 ft3
im only running a 600w hps

600w / 72 ft3 = 8.333w per ft3

not bad for half the recommended min :dance013:

6 plants crammed in there to lol
 

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Hydro-Soil

Active member
Veteran
that's what i am saying sure i am getting 40 watts per Sq foot an there are many running more watts per but when i see there harvests or bud shots well you be the judge :) :huggg: bud is on 5 gallon / 20 liter pail

It'd be smaller with higher wpsqft, but more dense. Size isn't always everything. :)

Not saying it isn't dense... lots of hybrids do well at lower levels, just saying that it would be denser still.

Looking nice there for sure. Whatever you're doing, it works... Keep it up! :D


Stay Safe! :blowbubbles:
 
my room is 4ft x6x 3 = 72 ft3
im only running a 600w hps

600w / 72 ft3 = 8.333w per ft3

not bad for half the recommended min :dance013:

6 plants crammed in there to lol

25 watts per sq ft? Excellent on the efficiency, Brother. What kind of yield do you get from those 6 plants?/strains?/how tall do you grow them?
 

guy fawkes

Active member
Veteran
25 watts per sq ft? Excellent on the efficiency, Brother. What kind of yield do you get from those 6 plants?/strains?/how tall do you grow them?

Cheers mate,
i average about 12-14 oz per crop and a finnish height of around 4 foot (2 main stems) give or take depending on strain ,
i grow in 12 l pots or coir/bat special , vegged for a good 2 weeks then topped and vegged for another 2 weeks,.. this will vary slighty strain to strain and the plants overall vigour .
feed wise
veg, plant magics oldtimers organic base feed, plant magics magic granules (friendly fungi's), multizyme,
bloom. canna terra floures base feed, molasses, vitalink buddy, h+g big bud xl calmag and and some AN big bud amino's, oh and silicon :)
no ph adjustment ever.
cost about £110 for 2 crops,
im treating myself to a digi 1000w adjustable after this crop as ive had the one im using has over 6 years of hammer so tbh doubt its putting the full 600w to the bulb, il still run 600w for the majority of the grow and crank it upto 1100w for last 4 weeks (its got 10% turbo booster button lol)
 
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medicalmj

Active member
Veteran
hey all whats the optimal wattage per Sq foot for growing i kinda always went by min 40 watts per

Come on Doc, you are a pro, you should know. But looks like we used to read the same grow books back in the 80s, which said 40 w per sq was the ideal number to maximize and not over do the electric bill.

Also, depends on light source. Assuming HPS, I like 40 plus reflective material right up to the plant on all sides. I make portable panels from 1/2 foam board and then place mylar on it. I hang em from the ceiling with small chains and j hooks so I can remove to access.
 
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DryNobBob

Sir, would a T5 for a light make any difference? Apologies if a stupid question. If you don't mind me asking, in your opinion. in a closet, 1.5 deep, 5' tall and 4' long, one T5, would be good or bad. By my calculations, is that 80w per ft3 if the t5 is 240W?

Come on Doc, you are a pro, you should know. But looks like we used to read the same grow books back in the 80s, which said 40 w per sq was the ideal number to maximize and not over do the electric bill.

Also, depends on light source. Assuming HPS, I like 40 plus reflective material right up to the plant on all sides. I make portable panels from 1/2 foam board and then place mylar on it. I hang em from the ceiling with small chains and j hooks so I can remove to access.
 

medicalmj

Active member
Veteran
Sir, would a T5 for a light make any difference? Apologies if a stupid question. If you don't mind me asking, in your opinion. in a closet, 1.5 deep, 5' tall and 4' long, one T5, would be good or bad. By my calculations, is that 80w per ft3 if the t5 is 240W?

Good question. T5 have a good lumen output at about 80 lumens per watt. HPS gets to 140, but not as much usable if you compare to the 6500k T5 bulbs. So I'd add a lttle to that 40, say 50+ watts per/ft.

Next, are you hanging that vert or horiz?

If horiz, then I'd say 240 is decent (6 sq ft = 40 watts per sq ft), but not going be that good for flower. If I had to flower under a T5, I'd want a very short plant and at least 60+ per/ft. And I'd mix some 3000k w the 6500k to get that extra red for flower.

If hanging vert., f*ck, idk. Have to think bout it...
 
D

DryNobBob

thank you sir. Horizontal, between the budget and the landlord, hehe.
 

mrcreosote

Active member
Veteran
They are hanging from my raptors and the next spot I can put them at would be 2 ft farther away.


How are you getting those raptors to stand still that long?
In Jurassic Park, they were always running around.
 

macumba

Member
optimum is what makes you feel good..

if that's a windowsill , or a 1000, or 2 small floros....


having fun is all that matters, and you'll know what wattage you should use, when you ask yourself honestly, what will make you happy

letting the good times roll
 

rangergord

Active member
For years I grew with a 400 watt HPS mag ballest lamp in a 4 x 2 space with 8 square feet with mylar sides. 50 watts per foot. Then I bought a digital ballast and was amazed that my plants grew much better at 250 watts. Temperature and humidity improved and yeild up.

I only turn it up when its serious bud baking time now.
 
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