Mistakes I made

[micmac]

Looking back at last 2wks when I went from led for seedlings and small plants to 600w hps here is what went wrong .

1.... plants dried out looked similar to nutrients burn

2.... humidity below 40% temps 28 to 31deg

3....unstable environment

4....amount of air exchange

After many countless hrs of watching and recording info , buying humidifier,searching web for hrs looking for something similiar,

No matter what I tried no improvement, clutching at straws I decided to switch exhaust fan off for a couple of days using the vents in the tent as ventilation so opened 1 vent at bottom 2 at the top and recorded info over next 2 days, well what do you know temp range 24to 30 deg constant for entire time humidity was 65/80% entire time .

The plants actually reach for the light now before they were limp and dry .Just to make sure I put a small clone in to see how it would respond,it has grown an inch in 2 days and showing no sign of stress.

It turns out the exhaust fan was way too big for this tent and was creating an unhealthy area, way too dry as all the moisture was been sucked out much like a dehumidifier,

Has anyone else experienced similar problems?

[Jim420]

We bought a 6" 150mm phresh hyper fan .. it's never on for too long . Like with your situation it just seems to suck everything out of the tent , even on low .. We grow with LED's and I'm just not sure if the CF we have is necessary ? I'd really like to get more people opinions on this ? Are huge Exhaust fans necessary for such small spaces ? Especially with LED's ?? Edited June 28, 2017 by Jim420

[Gumby1]

no.. with led or little heat producing grows.. you do not need such big exhaust.

 

maybe a 3" or 4" fan with a carbon filter.. and a small oscillating fan for air movement.

[Jim420]

no.. with led or little heat producing grows.. you do not need such big exhaust.

 

maybe a 3" or 4" fan with a carbon filter.. and a small oscillating fan for air movement.

Thanks gumby.. I just bought a new tent . It's 2.4x1.2x2 . Gonna have 2 solar system 550's in there . You still think 4" or should I go 6" just to be safe ?

[Gumby1]

are you going to have an intake fan aswell?.

 

or just the exhaust ?.

 

and is it a strong built tent?..

 

i have seen a cheeeep tent fold in on its self due to extreme exhaust.

[Gumby1]

got 2 600w vipaspectra LEDs in a 2.2 x 2.7 space.. i think it is.

 

with supplement lighting aswell.

 

still just the 4' with carbon filter and silver ducting exhaust. . seems to do the job.

[micmac]

got 2 600w vipaspectra LEDs in a 2.2 x 2.7 space.. i think it is.

 

with supplement lighting aswell.

 

still just the 4' with carbon filter and silver ducting exhaust. . seems to do the job.

from my experience a small exhaust fan my mate has same size all he uses is small exhaust fan and the plants are great it plugs into USB port on power board , if you have good temps the vents on the tent will do the job when I put my hand under vent in roof you can feel the air escaping I put the fan in front of lower vent to suck on fresh air works a treat remember carbon filters also suck moisture out very efficiently

[micmac]

We bought a 6" 150mm phresh hyper fan .. it's never on for too long . Like with your situation it just seems to suck everything out of the tent , even on low .. We grow with LED's and I'm just not sure if the CF we have is necessary ? I'd really like to get more people opinions on this ? Are huge Exhaust fans necessary for such small spaces ? Especially with LED's ??

if you running leds you only need small exhaust and fan in front lowest vent small tents can create a surprising vacuum type effect if you get 6"' or 4" do the math and u will realise the bigger the exhaust to bigger the intake you need if you remove too much air it's not a good thing

[micmac]

no.. with led or little heat producing grows.. you do not need such big exhaust.

 

maybe a 3" or 4" fan with a carbon filter.. and a small oscillating fan for air movement.

itchybromusic showed this chart about vapour pressure decifit tells you what humidity u need at what temperature it helped me get the air flow of tent just right and keep it there

[merl1n]

The airflow is not just about removing heat, it's also about air exchange.

As the plant gets bigger it will expel more waste into the air, that needs to be got rid of.

Also air flow around the buds assists in it evaporating reducing instances of mould

Air flow flexing the growing stems strengthens the stems as well, stronger stems can hold bigger buds upright.

 

The carbon filter is for odours. Depending on the filter size vs grow space will depend on the fan needed. Will a 4inch move enough air for your space?? I know with mine a 4inch fan isn't big enough to force the air thru the filter without back pressure and won't exchange enough for my space.

 

Merl1n