Is it time to switch to 12/12?

[keith1975]

Hi Keith. I read your problem and have scanned through the post. Do you have an exhaust fan pulling air from your tent? I don’t know your whole situation but this is what I would try to do. Seal one of your windows(use cardboard and a trash bag if you need to or a piece of a insulation cut to fit the window) except enough so you will have some air coming in still but little enough where you can control the climate in your basement. Seal your other window and set up your exhaust fan if you haven’t already and run some ducting from the exhaust fan directly to the hole in your second window. The pressure created by the exhaust fan will create a passive air intake for your tent just keep a few holes open slightly. Run your dehumidifier constantly in the room so you can try to create a sealed environment you made in your basement by sealing those windows and it will make it much easier to control the Rh in your tent once you get it lowered the basement. Don’t allow any run off water to sit in your tent because the lights will evaporate it all over the day time. My dehumidifier was originally around the same price but I bought it used and it comes with a hose on the back that I run directly into a five gallon bucket and it saved my grow this summer. Would fill the bucket easily in less than 24 hours. I hope this helps at all and gives you an idea of how to create a good environment. Sorry if I overly explained things. Take it easy - jodyhigjrollr

Extremely useful! Thanks! I wasnt sure what to do about the windows. And it does look like it could be the problem. I left the main door open for a bit and the humidity shot up. So def has an impact!

Is it good enough for the tent exhaust just to suck the air out of the tent or must it get sucked out of the basement too?

 

[keith1975]

Also, this happened to my autoflowers today:

Is my autoflower flowering?

 

[keith1975]

The money needs to be thrown at the room! Can it be sealed with something? Is it underground? I'm surprised you don't have mold growing all over the place in there .

Its not entirely underground. I can seal it yes, wasnt sure if that is the issue, but its sounding like it is. As for mold, this room did have mold problems in the past. I honestly also dont understand why there isnt mold everywhere.... is there a way to test for mold?

 

[jodyhighrollr]

Wait do you have an exhaust fan in your tent currently?

 

[Icemann420]

Wet lock paint. If it’s a brick room and cement floor moisture from outside will leach right through the brick. There a product at any home improvement store made by ugl called wet lock or dry lock. What it’s purpose is to keep the moisture from leaching through brick and concrete. Like basement walls that seeps water.

 

[keith1975]

Wait do you have an exhaust fan in your tent currently?

Yes, I do. Which sucks the air out of the tent and towards an air vent that takes the air out of the basement.

 

[InTheShed]

Wet lock paint. If it’s a brick room and cement floor moisture from outside will leach right through the brick. There a product at any home improvement store made by ugl called wet lock or dry lock. What it’s purpose is to keep the moisture from leaching through brick and concrete. Like basement walls that seeps water.

air vent that takes the air out of the basement

Does that air vent have an exhaust fan? If not, get one. You need to actively be removing humidity from the grow room. Putting a tent in a room known to have mold problems isn't a good idea without remediation.

 

[keith1975]

Also, this happened to my autoflowers today:

Is my autoflower flowering?

Seriously, does this mean it's flowering? Or is that just pistels growing before it actually starts flowering? I.e. Should I see this on my non-auto-flowers too?

 

[InTheShed]

That plant is flowering. If your photo-period plants (non-autos, aka "photos") are doing this under 18/6 or 20/4 lighting then they are autos! Photos don't do that until about a week+ after you change your lighting schedule to 12/12 (called "flipping").

 

[keith1975]

Does that air vent have an exhaust fan? If not, get one. You need to actively be removing humidity from the grow room. Putting a tent in a room known to have mold problems isn't a good idea without remediation.

The previous mold problem was resolved. The place was cleaned out and two windows were added. And no mold ever came back. Another project also saw the room being waterproofed from the outside. So besides for the floor, the room is fairly watertight.

I have, however, more information. The two windows in the room, I tried to close them using only duct tape for now. The duct take doesn't hold. Which means there is a serious breeze going through these windows. Furthermore, the second window which has the extractor fan is being blocked by the grid on the window. I.e. At full blast, not enough air is leaving through the grid. Which basically means most of the air coming out of my grow tent is going back into the grow room.

I do believe closing off the two windows is the next step. I can't control the air in the room with so much outside influence. So even if closing the windows might cause other issues, I don't see any other way. That has to be step 1. SO that's what I'm going to be doing today. Trying to find a way to close those windows that works better than duct tape. Any suggestions? Right now I'm thinking of glueing a tile over the 30 x 15 cm window. But glue will ruin the wall a bit. And look ugly. But cementing it closed is a bit extreme. Any temporary but reliable ways to do this?

Once I have the holes fixed, I might have to make circular hole in the grid to force the air out. But I really wish it wasn't necessary for me to also get the air out of the grow room. Is that really necessary? So it's not good enough to suck the air out of the grow tent, into the grow room. It must also be sucked out of the grow room essentially out of the building?

 

[keith1975]

That plant is flowering. If your photo-period plants (non-autos, aka "photos") are doing this under 18/6 or 20/4 lighting then they are autos! Photos don't do that until about a week+ after you change your lighting schedule to 12/12 (called "flipping").

That is amazing! That means the autos started flowering after 43 days. That's fast, right?

I am going to need to switch to 12/12 soon for the photos. I just need to sort out my humidity problem. When I switch to 12/12, the Autos are also going to get 12/12. I know it might be better to get two grow rooms, one for veg, one for flower, but that's not practically possible for me at the moment. So, when I do switch to 12/12, is the quality of my Autos going to go downhill?

 

[InTheShed]

That's a lot of info! Let's start with the basics. Plants transpire water which will raise the RH in the tent unless it's vented. In order to vent it, you need to pull outside air in. Whether that's a problem depends on the ambient RH in the room. If it's lower, great! If it's higher, you will need a dehumidifier somewhere. Where depends on how big it needs to be and how much heat it's going to generate.

Ignoring the heat issue for a moment, you are trying to hit a target RH in the tent based on the stage of growth: higher for veg, (50-65%) and lower for flower (40-50%). The ambient RH of your grow room and the ambient RH of the world outside will determine how to hit those numbers.

If tape won't hold then your options are glue and screws. If you use glue, it doesn't need to be epoxy strength so you should be able to find stuff you can pull off. Silicone caulk might do it if you use thin plywood. Tile would be much heavier and need stronger and therefore more permanent glue.

So, when I do switch to 12/12, is the quality of my Autos going to go downhill?

Not downhill, just smaller buds then they would have been under 18/6 or 20/4. With a mix of photos and autos in the same tent, it's always a trade-off. 43 days is not fast, it's great!

 

[keith1975]

In order to vent it, you need to pull outside air in.

So in other words, just like I have a tube going out with an extractor fan, I also need to add a tube coming in with air. And that air coming in, must have a low relative humidity, so as to aid in bringing down the humidity. BUT... and this is the part I need to understand:
a) can the air leaving the tent, go back into the grow ROOM?
b) or must it be extracted from the room?
c) or does it not matter, as long as the dehumidifier keeps the humidity down?

My concern is that I'm re-using the same air. Shoudn't new fresh air be introduced into the system in some way?

 

[InTheShed]

You don't need a tube for intake, just open one of the lower vents opposite the top exhaust vent.

a) it can go back into the room if the room can take the added RH without it getting too high. In a house, rooms are connected to other rooms and have heat or AC circulating air around the entire house. In a closed room it becomes much more problematic.
b) it must be extracted from the room if it would otherwise raise the room RH above the target level.
c) if you have a dehuey in the room, that would be a way to solve the rising RH problem, yes.

Fresh air should be introduced if only to provide CO2 to the plants.

 

[keith1975]

You don't need a tube for intake, just open one of the lower vents opposite the top exhaust vent.

a) it can go back into the room if the room can take the added RH without it getting too high. In a house, rooms are connected to other rooms and have heat or AC circulating air around the entire house. In a closed room it becomes much more problematic.
b) it must be extracted from the room if it would otherwise raise the room RH above the target level.
c) if you have a dehuey in the room, that would be a way to solve the rising RH problem, yes.

Fresh air should be introduced if only to provide CO2 to the plants.

Thank you! Very useful!

Last question. How would you introduce fresh air? Opening the door every other day? Because keeping it open increases humidity.

 

[InTheShed]

Then so will opening the door! That's what that expensive dehuey is for. What's the ambient RH for you this time of year?

 

[keith1975]

Then so will opening the door! That's what that expensive dehuey is for. What's the ambient RH for you this time of year?

The average relative humidity is 70% all year round.

 

[InTheShed]

70% is okay for veg with good airflow around the plants (read: oscillating fan). That said, 70% is what my plants live in most of the time since I grow outside during the day and in an un-insulated shed at night under LEDs. It's not ideal but there you go.

If you put the dehuey in the room, what can you get the room RH down to?

 

[keith1975]

If you put the dehuey in the room, what can you get the room RH down to?

I closed the two windows and the room went down to 55. The one window still has the extractor fan and i think some air is leaking in from there. So im going to let the extractor fan blow the air out of the tent and into the grow room. And completely seal that Window. Pretty sure thats going to get me down to at leat 50! So yes, your room needs to be completely sealed. At least in my case it does...

 

[InTheShed]

55% is fine if you can keep it there all grow. In flower just make sure you have a fan blowing inside the tent to circulate the air. Don't knock yourself out to get to 50%, It's not a magic number.