Is a 400W HPS *too* much for 3 sq. ft?

S

sakeser

Active Member
so I have heard that you can never have too much light. I have also heard that you want somewhere between 3,000 - 6,000 lumens/sq. ft. I am going to use a 400W HPS outputting about 50,000 lumens, to about 3 sq. ft, so that is about 15,000 lumens/sq. ft.

My question is, is this too much?

(this is a side note, but I am vegging with 14 23W 6500K CFLs, 10 on top, 4 sub canopy)
 
T

Tree of Life

Active Member
On a clear summer day, the sun puts out 10,000-12,000 lumens psf. you would essentially have the sun in a box, which would make for some very happy plants. so long as they have room to grow and it's not too hot, they should do very well
 
theotherc

theotherc

Well-Known Member
How high is the box? 3x3 works great for a 400. Just make sure you have some space when they grow up and enough vent. to get airflow through. If it's a batwing type reflector, I recommend doing a home made cool tube. It will keep it a few degree's cooler in there.
 
S

sakeser

Active Member
My cabinet is 1.5' x 2.5 ' = 3.75 sq ft.
The height is roughly 7'.

I don't have a reflector for it. I am considering making it myself somehow. For ventilation, I have a 1'x1' fan (no CFM specified) but I think it should be sufficient to exhaust the excess heat from the HPS.

I was thinking of just mounting the light on a white board and having the board be adjustable height in the cabinet. I don't know if I would be able to find a parabolic or dish reflector with the right dimensions.

I was initially planning on just using CFLs (maybe 12 23W 2700K CFLs), but now I am getting a 400W HPS with ballast and 2 bulbs for $50, barely used. From what I have read on this forum (btw I love you all!), HPS is the shit! So I will try it out.
 
S

sakeser

Active Member
Question:

Do I need to add ventilation for the bulb itself? I am reading a lot about "cool tubes" and stuff. Do I need to have a cooling with a conduit near the bulb for air flow on it, or can I just have like a 500 CFM fan exhaust my whole cabinet?
 
theotherc

theotherc

Well-Known Member
sakeser said:
Question:

Do I need to add ventilation for the bulb itself? I am reading a lot about "cool tubes" and stuff. Do I need to have a cooling with a conduit near the bulb for air flow on it, or can I just have like a 500 CFM fan exhaust my whole cabinet?
Click to expand...
yeah you need some form of vent for the cooltube. use vent hosing on eachside, run a fan through it when the light is one.
 
calicat

calicat

Well-Known Member
sakeser said:
so I have heard that you can never have too much light. I have also heard that you want somewhere between 3,000 - 6,000 lumens/sq. ft. I am going to use a 400W HPS outputting about 50,000 lumens, to about 3 sq. ft, so that is about 15,000 lumens/sq. ft.

My question is, is this too much?

(this is a side note, but I am vegging with 14 23W 6500K CFLs, 10 on top, 4 sub canopy)
Click to expand...
your actual goal is 10,000 lumens. With a 400 W HPS fixture if you keep it at a distance of 2.25 ft from you canopy will acheive that goal.
 
C

cruzer101

Well-Known Member
Yea it works fine if it is vented properly.

I have a cabinet thats 36" wide by 18" deep.
The cooltube is a great idea but it is 19" long and I wanted to go sideways.
So I made a cool tube out of a bake-around I got on ebay.

Then got a 120cfm duct booster and mounted it behind the cabinet and suck air through
the tube to cool the light and exhausts the cabinet at the same time.

I added a second exhaust fan for the tops of the plants and have a 120cfm intake by the bottom
of the plants. My lights run at night 8 to 8 and I have no problems.
Temps run a little high about 89-92 I just stay with a sativa dominate strain. The screen keeps them at the proper height.

As you can see I also use LED and T5 5000k for side lighting

Here are a couple pics, I got a scrog goin on.
 

Attachments

H

hybrid

Well-Known Member
there is no such thing as too much light so long as you can deal with the heat issues.

If you can keep the temps down, you should be a happy happy guy.
 
buster7467

buster7467

Well-Known Member
cruzer101 said:
Yea it works fine if it is vented properly.

I have a cabinet thats 36" wide by 18" deep.
The cool tube is a great idea but it is 19" long and I wanted to go sideways.
So I made a cool tube out of a bake-around I got on Eba.

Then got a CF duct booster and mounted it behind the cabinet and suck air through
the tube to cool the light and exhausts the cabinet at the same time.

I added a second exhaust fan for the tops of the plants and have a CF intake by the bottom
of the plants. My lights run at night 8 to 8 and I have no problems.
Temps run a little high about 89-92 I just stay with a saliva dominate strain. The screen keeps them at the proper height.

As you can see I also use LED and T 5000k for side lighting

Here are a couple pics, I got a scrog goin on.
Click to expand...


You can drop the temp in your grow room if you get rid of that shiny bubble wrap insulation that you have up to reflect the light and put up either mylar or just painting the inside flat white. I used to use the shiny insulation like that but was having temp problems and when i took it down and just painted the inside flat white the temps dropped about 6degrees, no lie. You really need to bring those temps down and that would be the easiest way to do it. But the setup looks good. Can't wait to see how it turns out. Good luck.
 
S

sakeser

Active Member
so the guy I was suppose to get the 400W HPS kit from bailed, so I actually just got a 250W HPS ballast kit off ebay for a great price! I figure this is sufficient for my cabinet and will be easier in terms of ventilation requirements. I will probably just have a 10" fan out-taking at the top. Just need to have it light tight.
 
S

stonecold

Well-Known Member
I just got my 400w hps/mh kit, I also just got my romulan/diesel seeds. now im off to home depot to built a super box, so all this info is gonna help me make the right box. once i get it built, i will be starting a grow journal too. the ideal set up im thinking is, 400 mh/hsp at top. 4 light bars with 6 23w cfls on each wall. going from bottom to top of the sides. 2 inline fans drawing fresh air in from the bottom and 2 exaust fans for heat at the top. oh yea, also, it is going to be fed fresh air from my fireplace in the basement, and with winter on the way, it will be very easy to keep it cool, maybe i might need a heater? lol idk, i got my 400w hps/mh from htg, ballast, 2 bulbs, socket, batwing reflector, timer, all that for $189 total, ups dropped it off yesterday.
 
allovher

allovher

New Member
are you sure there can't be too much light? with a 400mh less than a foot away seemed to give the plants a bleach effect. the heat was only 80F
 
M

monkeybones

Well-Known Member
You wont have much problem. Most of the issues arrise from lights being too close to the canopy and burning the leaves. Raising the light always accomodates for over-powerful light sources.

You can also avoid most heat related issues by simply having a decent fan blowing across the top of the canopy to keep your girls cool and happy.

I also use a 400w HPS, but in a larger space. I have so far met with success. But as others have said, smaller spaces often call for some ventiliation of the light to avoid fire hazard and heat buildup. I would reccomend making sure the heat blasting off the top of the light gets nowhere near your girls, which might imply different things depending on your particular circumstances.
 
L

LittleGreenMan1

Member
i'm going to say your all wrong. i had 1400w in a 4'9'' x 4'9'' and my plants looked healthy but never grew.

they were just fried into submission. temps were around 80 and ph of the water was fine.

once i switched to JUST the 400w metal halide bulb they took off like rockets.

i agree that you can't damage your plants with too much light, but you want them to reach for the light once they can support their own weight, this makes room for budsites and more nodes (where the bud forms)
 
Werry420

Werry420

Active Member
i currently use a 400HPS in a room about 3feet by 3feet by 3feet high and it is perfect... as along as you keep em small and not to close to the night... the temp in my room reads 25 at the hottest point in the room and about 17 at the coldest point in the room when the light is off.... KEEP IT GREEN
 
You must log in or register to reply here.
Top