8x8 tent, humidifier, FAN exhaust and HVAC questions!?!?!?!?

So the room I'm growing in is roughly 14x10x8

I've got an 8x8x6.6 tent and a 3.5x3.5x6.6 tent in there at the moment.

One veg, One grow

My rafters are accessible. It's not drywalled. Its got these metal frames with little decorative insulation on there. I can easily take these out.

As of right now I'm exhausting my veg tent through my window with this little setup

When I move to my 8x8 tent in a few weeks.
I'll be using 2x 6" vivosun fans no filter hooked up the same way.


Now my 4" fan I'm using at the moment does a good job keeping temps and humidity down in the 3x3 tent.
No exhaust runs at night
So nighttime humidity levels climb to 50-80%

I do not want to have this problem when I move to the flower tent.

The 2x6" vivosun was all I could afford for the time being since I'm already 3600 into my setup and haven't had a crop yet.

I'm GOING to need a decent humidifier to prevent bud rot.

And next grow I'm going to upgrade to 8 or 10" fans and have some ducting plumbed in properly. Venting outside


My questions.

-What size\brand of humidifier would you guys suggest to keep humidty sensible in a 8x8 tent

I read somewhere that 1 gallon of water holds 8 pints.
So when in watering my 7 gallon pots they might take a 1 gallon each in flower?
Since I have 4 pots, that's 4 gallons x 8 pints equals 32 pints I would need roughly?

-is the inline fan and ducting setup more sensible and cost effecting than a small HVAC setup?
(And would hvac even be an option)

Cheers

What lighting are you running?

boilingoil said:

What lighting are you running?

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1x600 watt hps (open ended
1x 630watt power draw cob\led fixture
3x 240watt power draw cob fixtures

Not enough lighting for a full 8x8, 22 wsf wont cut it.

boilingoil said:

Not enough lighting for a full 8x8, 22 wsf wont cut it.

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Mabne not bro but Its what I got for the time being.

The tent will have an isle down the middle and I'll have a scrog.
4 plants

1x600 watt hps for a 4x4 section
1x 6 cxa 2540 cob led & 80chip led 4x4 section
3x 4 citizen 1212 cob fixtures for a 4x8 section

Should decent enough coverage and penetration.

That being said more worried about exhaust and dehumidifiers than lighting.

Run your exhaust 24/7. See where that put you on RH

JungleSlut said:

Mabne not bro but Its what I got for the time being.

The tent will have an isle down the middle and I'll have a scrog.
4 plants

1x600 watt hps for a 4x4 section
1x 6 cxa 2540 cob led & 80chip led 4x4 section
3x 4 citizen 1212 cob fixtures for a 4x8 section

Should decent enough coverage and penetration.

That being said more worried about exhaust and dehumidifiers than lighting.

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So it would be more like 4 3x3 or 2 3x8.
70 pint dehuey you will need, not only do you have to take into the plants transpiration but ambient RH also and those swings.

boilingoil said:

So it would be more like 4 3x3 or 2 3x8.
70 pint dehuey you will need, not only do you have to take into the plants transpiration but ambient RH also and those swings.

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Cheers bro
thanks

What are your ambient humidity levels? Note that when air cools it holds less water so the RH% goes up. Definitely run the ventilation 24/7 if the ambient RH% is low enough. If the ambient RH% is high then you need to run a dehumidifier and not vent.

boilingoil said:

Not enough lighting for a full 8x8, 22 wsf wont cut it.

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Need to get my first grow over with and maybe another done then gonna do a DIY qb setup or DIY cob. We will rectify the wpsf

Renfro said:

What are your ambient humidity levels? Note that when air cools it holds less water so the RH% goes up. Definitely run the ventilation 24/7 if the ambient RH% is low enough. If the ambient RH% is high then you need to run a dehumidifier and not vent.

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Ambient as in outside temperature? 30% rh in the winter and spring. 40-60% in the summer.

No air conditioning in my house. Grow rooms in underground basement so temps are 4-7 degrees celcius cooler.

Might get another fan to run tent exhaust at night. Definately getting a big enough dehumidifier tho. Dont want to play around with bud rot. Too much invested to just scrape by

JungleSlut said:

Ambient as in outside temperature? 30% rh in the winter and spring. 40-60% in the summer.

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Ambient meaning outside the tent. If you are venting your pulling in air from outside the tent right? What is that air running on temp and humidity? You will never be able to get it lower that those numbers if you are venting. A dehumidifier won't help much if you are venting for heat as the air is constantly being exchanged. So if the air outside the tent is say 60% then you can't get the tent below that number venting. You may need an AC, that will also dehumidify some and eliminate venting for heat. Then a dehumidifier for when the lights are off and maybe a little help when the lights are on. If gets much more complicated if the ambient humidity is high.

A downside to a dehumidifier is it will add some heat to the equation as well. That might be helpful sometimes and bad other times.

Renfro said:

Ambient meaning outside the tent. If you are venting your pulling in air from outside the tent right? What is that air running on temp and humidity? You will never be able to get it lower that those numbers if you are venting. A dehumidifier won't help much if you are venting for heat as the air is constantly being exchanged. So if the air outside the tent is say 60% then you can't get the tent below that number venting. You may need an AC, that will also dehumidify some and eliminate venting for heat. Then a dehumidifier for when the lights are off and maybe a little help when the lights are on. If gets much more complicated if the ambient humidity is high.

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Ok so if I got a de-humy. Put it outside of the tent in the room. Ran that. Then had a fan inside the tent pulling in air at lights iff that would keep heat from the humidifier directly out of my tent more or less and maybe better than dehumidifier in the tent itself?

JungleSlut said:

Ok so if I got a de-humy. Put it outside of the tent in the room. Ran that. Then had a fan inside the tent pulling in air at lights iff that would keep heat from the humidifier directly out of my tent more or less and maybe better than dehumidifier in the tent itself?

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Well it will dehumidify and heat the air the tent is grabbing for intake. You are also pulling air from that room and thus new air has to come in so the dehumidifier will constantly be fighting the ambient humidity.

Really you can play around with different setups and perhaps find something that will work but the simple clean solution if you have a dual hose portable AC and dehumidifier and run the room sealed with no venting, just vent the tents right back into the room and not outside then you can really control humidity at the expense of having to cool the entire heat load with AC and having to supplement CO2 or just run vent cycles to bring the CO2 levels up to ambient.

Renfro said:

Well it will dehumidify and heat the air the tent is grabbing for intake. You are also pulling air from that room and thus new air has to come in so the dehumidifier will constantly be fighting the ambient humidity.

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You've given me alot of options for sure and I appreciate it ren

Read this on growweedeasy.com
""""With bright grow lights (such as 600W HPS and brighter), cannabis plants of all stages can thrive at slightly higher temps up to a max of about 85°F (30°C) even with no CO2 enrichment, as long as there is low relative humidity and plenty of air movement.""""""

It sounds as long as I can keep the humidity low and temps down I should be alright. If not I'll have to spring for an air conditioner.

Would love to do a sealed room. My basement downstairs isnt drywalled on the ceiling so it would never seal properly

Renfro said:

Really you can play around with different setups and perhaps find something that will work but the simple clean solution if you have a dual hose portable AC and dehumidifier and run the room sealed with no venting, just vent the tents right back into the room and not outside then you can really control humidity at the expense of having to cool the entire heat load with AC and having to supplement CO2 or just run vent cycles to bring the CO2 levels up to ambient.

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Hi Renfro
This sounds like a possible solution to my issues.
When you say "... and run the room sealed with no venting" - are you talking about the tent or ambient room it is in?
So the A/C would be circulating cooled/dehumidified air in the room, to and from the tent?
Hoping I got that right? (Taking notes.)
Thanks!

SatIndy said:

When you say "... and run the room sealed with no venting" - are you talking about the tent or ambient room it is in?
So the A/C would be circulating cooled/dehumidified air in the room, to and from the tent?

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I mean seal the room and vent the tents to and from that room. Cool and dehumidify the room air. You would need to monitor co2 levels and either vent for Co2 or add co2 with a bottle or generator.

Renfro said:

I mean seal the room and vent the tents to and from that room. Cool and dehumidify the room air. You would need to monitor co2 levels and either vent for Co2 or add co2 with a bottle or generator.

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Awesome, thanks a lot!
May very well solve some potential issues