2 x 400w grow tent

Danny1987

Danny1987

Well-Known Member
Hey all,

About to begin my next grow, see below setup:

1.5x1.5x 2m (5 foot by 5 foot) decent grow tent
2 x 400w MH / HPS (digital ballasts)
Adjust a wing medium reflectors
6inch exhaust fan with carbon filter
coco mixed with perlite
a&b nutes with silicone

Grow technique - LST & SCROG through mesh.

Goal - maximum yield and turnaround time.

Questions:

1. How long would you recommend i VEG for (how long is enough to LST for SCROG)?
2. Is the 800w enough for the size of tent?
3. Will i have issues keeping it cool? In my garage and approaching winter with a daily mean of min 12deg max 17deg.
4. I have 400w MH bulbs for VEG, should i set the ballast to high power for seedlings? or say 25%?
5. anything else i should get to maximize this grow?

Thanks for your help chaps.
 
coreywebster

coreywebster

Well-Known Member
Hey!

1. Your veg time depends on plant count, less plants will take longer to veg to fill your space. The more intense the light the quicker they will grow. I would look at a scrog guide , you will probably find topping a couple of times will give you more symmetry than lst which would be better for SCROGs.

2. You want a 1000w light for flower under one reflector in a 5x5

3. No you shouldn't have a problem with those temps if you have a good extractor fan and remove the heat out of the tent and garage.

4. Start seeds at low power and increase as they grow.

5. You want good air movement within your tent when you scrog. Get a bottle of cal/mag, you may need it, make sure your ph is correct and water until run off. Some good coco threads and growers on here to check out. Read plenty. Don't overfeed.
If your garage has a concrete floor use a layer of rigid insulation under your tent so roots don't get too cold.
 
Danny1987

Danny1987

Well-Known Member
I will have my 6 inch exhaust fan for air extraction. Would it be worth getting another inline fan at the base of the tent to bring air into it? Or just have some ducting exiting out the bottom of the tent to provide new air?
 
B

Bookush34

Well-Known Member
Better off with 2x 600s then 400s. I’ve rant dual 400s. Never was too excited.

2fans is best.
1 cosistantly pulling air threw the hood. And one on a tstat to exhaust the tent.

No need for intake Fans.
 
coreywebster

coreywebster

Well-Known Member
Sorry danny i didnt see your message.
Hit the reply button dude then folks get notified!
Anyhow Bookush answered fair!!
 
Danny1987

Danny1987

Well-Known Member
coreywebster said:
Sorry danny i didnt see your message.
Hit the reply button dude then folks get notified!
Anyhow Bookush answered fair!!
Click to expand...
Will do with the reply function from now on and thanks for the reply Bookush.

Corey, In terms of the 600s, im pretty stuck atm with 400s as i have bought them.

My idea is to have the two 400w HPS's side by side in a adjust a wing defender reflectors. No cooltube.

Will this be far too hot? Keen to work with the equipment ive already bought.
 
doeboi24

doeboi24

Well-Known Member
There about 3 feet tall in 3 gallon pots. Yes u do need cool hood if not running ac. I have 1 exhaust carbon and to intake fans ducting one of the fans from my central ac into the tent
 
Last edited:
coreywebster

coreywebster

Well-Known Member
Danny1987 said:
Will do with the reply function from now on and thanks for the reply Bookush.

Corey, In terms of the 600s, im pretty stuck atm with 400s as i have bought them.

My idea is to have the two 400w HPS's side by side in a adjust a wing defender reflectors. No cooltube.

Will this be far too hot? Keen to work with the equipment ive already bought.
Click to expand...
If its going to be too hot is a matter of how much air exchange and your ambient temps.
You ambient temps look good to me. You can afford like a 9 degree Celsius rise from ambient based on your higher temp reading and more on your lower temps.
So it just comes down to airflow/air exchange. I no longer have the chart available to tell you exactly how much cfm you need to get that specific rise from ambient.
But the math is as follows.

It boils down to CFM = 3.16 x Watts / DT(°F)

Watts is the lighting power (and any other 'hot' things in the grow space) in Watts.
DT is the allowable temperature rise within the enclosure (i.e. desired temperature minus ambient temperature) in °F.

So, to work out the size of fan required (in CFM) simply plug your lighting Wattage into the equation along with the DT value.

Should be 158cfm, but that doesn't take in to account your resistance for your filter and ducting which will reduce your airflow (add 25%) nor does it take into account any other wattage your running, since that info is not available to me.

IME, I can run 2x 600w hps in a 4x8 in summer without aircooled hoods, but if I want 3x 600s I have to air cool them all to have roughly the same temps.
All you can do is set it up and test it out since you have the equipment already. I think you will likely be fine temp wise provided you don't stick your thermometer directly under your lights.
 
Danny1987

Danny1987

Well-Known Member
coreywebster said:
If its going to be too hot is a matter of how much air exchange and your ambient temps.
You ambient temps look good to me. You can afford like a 9 degree Celsius rise from ambient based on your higher temp reading and more on your lower temps.
So it just comes down to airflow/air exchange. I no longer have the chart available to tell you exactly how much cfm you need to get that specific rise from ambient.
But the math is as follows.

It boils down to CFM = 3.16 x Watts / DT(°F)

Watts is the lighting power (and any other 'hot' things in the grow space) in Watts.
DT is the allowable temperature rise within the enclosure (i.e. desired temperature minus ambient temperature) in °F.

So, to work out the size of fan required (in CFM) simply plug your lighting Wattage into the equation along with the DT value.

Should be 158cfm, but that doesn't take in to account your resistance for your filter and ducting which will reduce your airflow (add 25%) nor does it take into account any other wattage your running, since that info is not available to me.

IME, I can run 2x 600w hps in a 4x8 in summer without aircooled hoods, but if I want 3x 600s I have to air cool them all to have roughly the same temps.
All you can do is set it up and test it out since you have the equipment already. I think you will likely be fine temp wise provided you don't stick your thermometer directly under your lights.
Click to expand...

Thanks Corey, I'll keep you posted
 
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