Humidity :( secret jardin

[SecretJardinDS90]

Hey all I'm new here :)

Clearly I have a secret jardin as per my name. It's 3x3x4.5 ft. I have 4 2ft T5's on ballast an a 3 speed fan. Here's my problem. I put on a dehumidifier out side my tent cause the basements RH was 90% I've got the basement down to 60% RH but inside my tent when lights on temp is 26*C (perfect) and 60% RH (not bad) the REAL prOblem is when the lights go off. The temp goes to 20*C and back up to 90% RH what do I do ?

Also! I have no intake/exhaust fans. I closed the bottom flap and opened the top one to let heat escape

 

[Dr.X]

Welcome Jardin secreto. You should get at least an exhaust fan to get air circulation, that should fix your problem.

 

[SecretJardinDS90]

Welcome Jardin secreto. You should get at least an exhaust fan to get air circulation, that should fix your problem.

I was thinking about that, what size though ? 4 inch ? 6 inch ? Also the one thing I do t understand is how can there be air flow with just an exhaust, I know I should be creating negative pressure correct ? I just don't want to have to buy 2, one for in and one for out

 

[Dr.X]

If you have only exhaust fan, your intake will be passive, I mean, the air will circulate without any intake fan as longest your exhaust fan can deal with the back pressure (I don't know if this is the right way to say it in English) that creates your system. And by system I mean any kind of element (filter, ducting...) that creates resistance to the air flow.

Now, maybe some body else have a similar setup and can help you to choose your fan, but If I where you I would go with the 6 inch one. Is better to have more air flow than not having any, and you can always buy a fan speed control if you think your fan is too big.

 

[SecretJardinDS90]

Thanks dr.X , looks like I'm gonna make a stop at home depot tomorrow. I'll post a pic of the babies in a minute

 

[SecretJardinDS90]

Heres the babies at day 6!!

 

[Dr.X]

Your welcome SJ, those babies are looking good. What strains are you running?

 

[LexLuthor]

Get an exhaust fan and just keep a hole open in the bottom of your tent opposite of the exhaust. That will cause air being sucked in through the bottom of the tent and circulating around your room then out the top, don't forget to keep a small oscillating fan in the tent 24/7 to help circulation. The reason RH raises at night is because of the plants transpiring, which causes them to release moisture. So the ventilation system explained above will move the humid air out of the tent. I'm not sure if transpiration is the only reason RH gets higher at night, but its the main reason. Anyways you got seedlings, they actually grow better in high humidity, now if they were in flower with big buds then the high RH would be alot more dangerous, but during the early stage of veg its not that big a deal.

If you need to know what kind of fan to buy, just find out the cubic feet of your tent. Multiply the height by width by length of your tent and it gives you the cubic feet which is 40.5 feet. Inline fans are rated by Cubic Feet a Minute (CFM) so you wanna get a fan thats at least 80 CFM so its double what the size of your tent is.

 

[SecretJardinDS90]

Get an exhaust fan and just keep a hole open in the bottom of your tent opposite of the exhaust. That will cause air being sucked in through the bottom of the tent and circulating around your room then out the top, don't forget to keep a small oscillating fan in the tent 24/7 to help circulation. The reason RH raises at night is because of the plants transpiring, which causes them to release moisture. So the ventilation system explained above will move the humid air out of the tent. I'm not sure if transpiration is the only reason RH gets higher at night, but its the main reason. Anyways you got seedlings, they actually grow better in high humidity, now if they were in flower with big buds then the high RH would be alot more dangerous, but during the early stage of veg its not that big a deal.

If you need to know what kind of fan to buy, just find out the cubic feet of your tent. Multiply the height by width by length of your tent and it gives you the cubic feet which is 40.5 feet. Inline fans are rated by Cubic Feet a Minute (CFM) so you wanna get a fan thats at least 80 CFM so its double what the size of your tent is.

Hey thanks lex, and thx dr. For the thumbs up on my babies!

So how would I install it ? Just slip it in the sleeve and close the draw string ?

 

[LexLuthor]

Hey thanks lex, and thx dr. For the thumbs up on my babies!

So how would I install it ? Just slip it in the sleeve and close the draw string ?

Your gonna need more then just a string to hold it, I think whatever bolts and screws you need would come with the fan.

 

[SecretJardinDS90]

Your gonna need more then just a string to hold it, I think whatever bolts and screws you need would come with the fan.

How would I screw it into the tent ? I don't think Ill be doing that, thing cost me good money

 

[LexLuthor]

How would I screw it into the tent ? I don't think Ill be doing that, thing cost me good money

No, not the tent, there should be brackets you screw the fan into, then the brackets get tied to the tent.

 

[SecretJardinDS90]

No, not the tent, there should be brackets you screw the fan into, then the brackets get tied to the tent.

All I see is the sleeves with the draw string... The only brackets I see are up top holding the lights

 

[LexLuthor]

All I see is the sleeves with the draw string... The only brackets I see are up top holding the lights

What about the fan, doesn't it come with brackets you tie to the tent using the strings, then you screw the fan into the brackets, right??

 

[SecretJardinDS90]

What about the fan, doesn't it come with brackets you tie to the tent using the strings, then you screw the fan into the brackets, right??

Ok there's 2 holes, one at the bottom and on on the ceiling, so put the exhaust on which one? Also open the other hole to bring in fresh air? Sound right?

 

[Dr.X]

Get an exhaust fan and just keep a hole open in the bottom of your tent opposite of the exhaust. That will cause air being sucked in through the bottom of the tent and circulating around your room then out the top, don't forget to keep a small oscillating fan in the tent 24/7 to help circulation. The reason RH raises at night is because of the plants transpiring, which causes them to release moisture. So the ventilation system explained above will move the humid air out of the tent. I'm not sure if transpiration is the only reason RH gets higher at night, but its the main reason. Anyways you got seedlings, they actually grow better in high humidity, now if they were in flower with big buds then the high RH would be alot more dangerous, but during the early stage of veg its not that big a deal.

If you need to know what kind of fan to buy, just find out the cubic feet of your tent. Multiply the height by width by length of your tent and it gives you the cubic feet which is 40.5 feet. Inline fans are rated by Cubic Feet a Minute (CFM) so you wanna get a fan thats at least 80 CFM so its double what the size of your tent is.

Lex, transpiration of the plants as you said is one factor that increase RH (but plants transpire more at high temps), but also, if temps go down RH goes up cause

RH= (water vapour in certain volume)/(maximum water vapour in the same volume that air can hold at x temperature)

As temps go down, water begin to condensate so RH in the air goes down ;)

 

[SecretJardinDS90]

I'm at home depot right now, the smallest I can fid is a 4inch inline duct fan, should I buy it ?

 

[LexLuthor]

Ok there's 2 holes, one at the bottom and on on the ceiling, so put the exhaust on which one? Also open the other hole to bring in fresh air? Sound right?

Put the exhaust fan in the top hole (exhaust) and open the bottom hole (intake) to allow fresh air in the tent. Make sure you put the fan on the opposite side of the intake so the air goes from one side of the tent to the other for better air circulation.

 

[LexLuthor]

I'm at home depot right now, the smallest I can fid is a 4inch inline duct fan, should I buy it ?

Does it have a CFM rating??

 

[SecretJardinDS90]

Put the exhaust fan in the top hole (exhaust) and open the bottom hole (intake) to allow fresh air in the tent. Make sure you put the fan on the opposite side of the intake so the air goes from one side of the tent to the other for better air circulation.

It's a 4inch inline duct fan with 170 CFM