Light Advice for my first grow

Hello guys, thanks for clicking,

So i am closing in on my first ever grow and I wanted to seek some information on light setup, I have brought this up in a previous post although I wanted to renew the feed for more information.

I currently have a grow tent setup with the dimensions 120x60x180 [centimetres] which seems to be big enough [length ways] to hang two lights or so over say an estimated 5-7 plants. So my question is, in a space this size, would one 400w MH/HPS be sufficient enough to cover a grow of this range? I also have a 300w CFL which I intend to use during the seedling and veg stage and just maybe the whole grow, if more light is better right? I have one air cooled reflector to help diffuse the heat and wanted to know if fitting another 400w MH/HPS would be too much of a heat burden or would this be better for the amount of plants?

Also, would this mean I would have to run two 400w ballasts or is an alternative available?

Thanks again for those who posted on my last thread, the information is priceless!

For the purpose of more detail, i also have a 4" inline air extractor at the bottom of my tent bringing in air and will be purchasing a 6" RVk Fan kit to expel the hot air through the top of the tent.

So the sq feet of your grow tent is roughly 8 feet.

Let's assume that the standard 400w MH gives of 32 000 (I think that's how much it gives off), so that's 32 000/8 = 4000 so I think that's an ok range. My guess it should be fine. With a HPS it's going to be more lumens naturally.

Another measurment is 50 W per sq foot, and since you have 400W / 50 = 8, perfect. (although growers prefer 100W per plant, just to be safe)

I WOULD LIKE SOMEONE ELSE TO DOUBLE CHECK THIS.

Two 400watters? That could be hard, but if you put them both in air cooled hoods/cooltubes you should be fine.

And you shouldn't have the need for two fans, one good one will be enough for a passive intake and a small fan inside to circulate the air and disperse hotspots.

But to be honest you can definitely make do with one 400 watter, two could be a slight overkill.

Gregor Eisenhorn said:

But to be honest you can definitely make do with one 400 watter, two could be a slight overkill.

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thanks for the feedback, I'm still getting to terms with how much each plant desires and the lumens in relation to sq ft. so thanks for that

In regards to the air being pulled in and out, my 4" inline fan which will bring the air in, is bringing in room temperature air from my bedroom, and the air which will be pulled out would be then pushing it back into my bedroom, would the air thats extracted need to be pushed outside the house or would it be fine to just circulate in the room aslong as fresh air is available from open doors and windows?

Thanks again!

It's fine, you don't have to extract it outside unless the grow tent is in a small room. Just make sure to open those windows/doors from time to time to circulate the air.

Unles you'll have heat problems, which in that case you'll have to vent the air outside.

Check out passive and active intakes.

Do keep us posted!

I don't think I'd want to do more than 5 under 400w, I'm only going from my own experience and I don't really understand all the ways light is measured, I have 11 plants under 2 600w hps and I don't think I'd want more plants in there, I don't think I could keep any more than that evenly covered under both the lights, maybe one more at a push, just thinking of how the wattage covers the space. I'm by no means an expert grower and I've never used mh lights, but that's my take on it. Personally I think I'd want to be doing autos or keeping small plants if I wanted to run more than five under 400w.

Gregor Eisenhorn said:

It's fine, you don't have to extract it outside unless the grow tent is in a small room. Just make sure to open those windows/doors from time to time to circulate the air.

Unles you'll have heat problems, which in that case you'll have to vent the air outside.

Check out passive and active intakes.

Do keep us posted!

Click to expand...

thanks brother! shall do

Cannacat said:

I don't think I'd want to do more than 5 under 400w, I'm only going from my own experience and I don't really understand all the ways light is measured, I have 11 plants under 2 600w hps and I don't think I'd want more plants in there, I don't think I could keep any more than that evenly covered under both the lights, maybe one more at a push, just thinking of how the wattage covers the space. I'm by no means an expert grower and I've never used mh lights, but that's my take on it. Personally I think I'd want to be doing autos or keeping small plants if I wanted to run more than five under 400w.

Click to expand...

thanks bro, yeah Ive ben told I should focus on 5 to get the best out of them instead of sharing that much light around. I think I'm just a little yield hungry at the moment as the grow is for monetary purposes.

thanks again