4 vs 6 inch inline

Gonna be running a 400w MH/HPS in a 20 wide by 36 long by 64 high grow tent and have a few questions. I am going to be growing LSD seeds from Attitude in Fox Farms Ocean Forest.

1. I'm going to buy either a 4 inch high output fan at 170 ft^3/min or the 6 inch high output fan at 424 ft^3/min. Will the 4 inch be sufficient to cool the tent and keep temps around 76-78 given that I will exhaust the air out of the tent at the top and use passive intake leaving one of the flaps open at the bottom of the tent?

2. I was planning on going with just 2 plants and growing them to about 18-20 inches and then flowering. Taking into account their likely final height of 36 inches give or take, will the 400W HPS give me enough light penetration to still reach the bottom of the plants, or should I flower earlier?

Sorry about the wordy questions, just wanted to be thorough. Any advice is greatly appreciated.

EDIT: Had to add that the bulb and reflector will be aircooled

go with 6 inch if you dont care about sound, 6 inchers are loud but 4 arent that strong

aknight3 said:

go with 6 inch if you dont care about sound, 6 inchers are loud but 4 arent that strong

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Thanks for the advice, how much louder is the 6 inch compared to the 4?

well if i have my 6 inch on full blast i can hear it in my closet in another room... it def hums...

if ur gonna grow jus 2 plants, check this thread out.. this will allow light to get to the bottem of ur plants aswell... lots of benifits to this technique..
https://www.rollitup.org/advanced-marijuana-cultivation/136974-super-cropping.htmlhttps://www.rollitup.org/advanced-marijuana-cultivation/200413-fimming-m-blaze-complete-how.html

aknight3 said:

well if i have my 6 inch on full blast i can hear it in my closet in another room... it def hums...

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Thanks, gonna go with the 4 inch then as noise is a concern.

if ur gonna grow jus 2 plants, check this thread out.. this will allow light to get to the bottem of ur plants aswell... lots of benifits to this technique..
https://www.rollitup.org/advanced-mar...-cropping.html

Thanks for the info, I was planning on topping both plants once, and possibly twice depending on how they react the first time.

Anyone have info on how much light penetration I can get with a 400W HPS? Can I get 3 feet?

john84 said:

Thanks, gonna go with the 4 inch then as noise is a concern.

if ur gonna grow jus 2 plants, check this thread out.. this will allow light to get to the bottem of ur plants aswell... lots of benifits to this technique..
https://www.rollitup.org/advanced-mar...-cropping.html

Thanks for the info, I was planning on topping both plants once, and possibly twice depending on how they react the first time.

Anyone have info on how much light penetration I can get with a 400W HPS? Can I get 3 feet?

Click to expand...

u can top and then supercrop, thats what i did.. not sure if it will penatrate 3 feet but if u supercrop the light will get to those bottem nugs, like in my pic... jus grow as high as u can wide and then bend!!!