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Ventilation/Lighting Question

Ohmless

Member
I don't think two 250's would be overkill. Might be just about right for that garden footprint.

That is 62.5 watts per square foot. I currently run at about 100 watts per square foot to improve density of buds, but when I was happy with my results when I used 37.5(they weren't for trade though back then.)
 
when i first started, i used 3 150hps, and 4 or 5 42 watt cfl's. grew some of the best plants i have ever seen! now, many, many, ...... many years later ... lol i switched to led's. in between time i have used, 400w and 600w hps, but so hated the heat. in hind sight, i would stick to the 150's with some cfl's around the outside.

 

Zen Master

Cannasseur
Veteran
I say keep the T5 since you already have it.

If you can monocrop you'll be able to get your canopy perfect. Get the HID if you can step up to a 600 at least, just my opinion.

I did a T5 grow to find some genetics from seeds I created and had better results than expected. The varied stretch made some be 10" away from the bulb while other phenos were almost touching, that affected the outcome I'm sure but I still was very happy with the quality.

2x4 6 bulb T5, daylight spectrum bulbs :biglaugh:

did a coco bed in a 2x4 ebb/flow table, no containers. GH nutes.


a hybrid I created, Respect OG x Honey White bx2

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another of the creations, Tahoe OG x Honey White, this is T5 grown

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T5's dont produce airy nug if you got the right genetics :smoke:
 

truepunk87

Active member
I'm with Zen, keep the t5. I run a 4' 6 bulb in a 2x4x5 tent with a 4" fan and filter. I wouldn't go cheap on your filter though, a 4x12 phresh filter works great
 

blackosprey

Member
Jay, from what I've seen, the 200w CFL as your primary light source is probably goign to disappoint you, even if you ran 2 of them. My reason coincides with your "con" for using the cfl in the first place. It's only a single point of light that won't penetrate well on the plants outside of a small circumference. If you were going to go clf, go with more clfs of a lower watt in a wider coverage. I use 6 35w and 2 40 w cfls (290 w, can't remember the total lumens right now) in a 1.5'x 2.5'x3' tall box and have no issues with heat or light penetration, but really, it's because of the multiple points of light. If I only had the one 200w with subsequent bulbs to make my current wattage, I think I would have less than desired results
 

vukman

Active member
Veteran

A few questions

  1. Is two 250w HPS overkill for a 2x4x5 tent?
  2. Will a 4 inch inline (190CFM) fan be enough or 6 inch (440 CFM)?
  3. Are cheapo carbon filters on ebay any good?

Hi:
I've eliminated most of the quote because all I can really comment on is the fan. My tent, which I am including a picture of has a 6" inline as you can see behind the filter. The tent is a 2x4x7 but it's a bit larger than that on exterior.
It is one that has 3 speeds..I forget the actual draw on each speed but let me tell you. With the tent closed and just the flap vents open on the bottom of which there are 3 of them, the fan on setting 1 sucks the sides of the tent it!! ahahha..first time I tried it, I got worried. Needless to say that I've never tried the fan on setting 2 or 3 with the tent closed up. Tent open, sure, I had to check how loud it was and for leaks in the piping but closed...no damn way....worried the damn tent wil get sucked into the filter!! ROFL!! heheh..(j/king)
As for the cheapo filters. I'm sure they will work.........for a time. I got myself a 'Mountain Air' and yes, paid premium for it as well but I know I got a premium product which will last at least a year to 18 months if not longer. Especially since my air flow through it isn't the full rating cfm so I'm guessing I'll get at least 18 months out of it. I can't say as much for a cheapo filter although I could be wrong.
I am not the type of person to make assumptions...If I do not know, I'll say I do not know and in this case...well...I do not know..

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Good Luck
vukman
 
G

Guest 315072

wen i had a 400w mh and hps. i went to a art store.. and bought a piece of glass used to house candles .. and made my own cool tube out of it!!!! and got sick temps and used a 400w in a 4 wide 4 high 2 deep.. grow box in a closet.. and had great temps!
 

Mate Dave

Propagator
ICMag Donor
Veteran
Lighting:

Small HPS lights are perfect for growing cannabis in restricted space conditions. They produce the most light from a given amount of electricity of any suitable lamp for cultivation, and produce a spectrum that is favourable for flower growth.

The spectrum isn't the best for vegetative growth, but that not really important to sog/scrog growing, as the vegetative period is so short. Lights as small as 35 watts are available by stripping components from security lights commonly available at discount hardware stores.

250 watt lights can produce as much per square foot in sog/scrog conditions as 1000 watt lights in room growing.

A single 70 watt light can produce enough for an average pot smoker in a space as small as 1 sq. ft.

CMH lights are available in small sizes, but they produce less light and more heat than their HPS counterparts, and heat is an important consideration in cabinet-style growing.

Regarding fluorescent lamps, the light to heat ratio is even worse, and I am not aware of any situation in micro and mini growing where I would favour them over small HPS lights.

Note: These lights are quite weak compared to 400, 600 or 1000 watt lights used in production growing. Intensity means that the light can be father away from the plant and still be bright enough at the bud surface to produce.

Light Intensity is a necessary for tight bud formation.

To get the most out of a small HPS light, you must keep the bud sites within the productive range of the bulb, a lopsided sphere extending out from the lamp source.

For a 250 watt light, that circle of light extends out about 20" from the lamp. For a 70 watt light, the maximum distance is apparently around 8"

A group of tall, skinny plants under such a light would only be properly lit at the very tops of the plants, leaving the bottom parts shaded out and in a low intensity light field, producing small, lightweight buds at best.

Ideally you would like all the buds within that magic circle of light intensity, and you would like that sphere of light completely filled with buds.

Ventilation:

If you would like to calculate the size of fan you require simply follow these instructions:

Measure the Height, Length and Width (in millimetres) of the growing environment.

Multiply together (H x L x W) to give the cubic meter volume.

Multiply this figure by the number of times per hour you want to exchange the air in the growing environment.

This will calculate the size of fan required to change the air at your desired rate per hour.

Say you choose 2 times a minute which is 120 per hour.

Buy the fan slightly above the figure calculated if possible to ensure adequate ventilation.

If you room is to work with negative pressure the extractor fan must work harder than the in-let fan if your to use a 2 fan setup.

Without a 2 fan setup the extractor I would over rate and get the slightly bigger one to ensure adequate ventilation.

If you can combine the use of oscillating fans to insure good air circulation around the plants with no hotspots.
 

handyandy

Active member
Lighting: T-5 will be fine. You will se best results if you use both 6500k and 2900k tubes. this will give you a better spectrum and produce better buds with a florecent fixture.

Vent: I use a Sun leaf 4" inline fan with a carbon filter on a 4'x7' room exits out sidewith a passive intake from inside my house. This gives me plenty of neg preasure and no smell.

Hope this helps
 

Hydro-Soil

Active member
Veteran
I suggest going with 2 250w CMH lamps, if possible.

You'll get the right light density/penetration and the lowered infra-red output will reduce your heat issues.

It's really going to depend on the speed of your fan and how well the inlet temps can be maintained.

T5's make great veg lamps since the penetration is perfectly adequate for vegging.

Stay Safe! :blowbubbles:
 

VerdantGreen

Genetics Facilitator
Boutique Breeder
Mentor
ICMag Donor
Veteran
i would say,if you are going to buy a new lamp, then go for 2 x 250 hps. flouros actually give out quite a lot of heat too and with the remote ballasts of the hps you can keep them outside the tent .
ive used cmh and didnt find them as good, plus you get complications with type of ballast etc.
ive also used flouros and they work fine, but hps is MUCH butter imo

now i use LED's which are great too but very expensive

good luck - check my diaries to see how i did with a 250 hps scrog in a cab half the size of yours.
if you get it dialled in you could get a pound and more per harvest with 2 x 250 hps. no way will you get that with flouros

VG

VG
 
Z

Ziggaro

I think you'll be fine with ventilation.. I use a Can 6" matched with a Can 33 which exhausts 178 CFM. I have a 600 Watt HPS in a roughly 3 x 4 space and temps stay below 80, so I think your exhaust will be fine.
I don't have any experience with stuff on Ebay but my can/filter setup was a little under $200 which I didn't think was much considering.
 
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