I have a 4x4x6 grow tent in my basement with a 6’’ vent fan and duct. my basement is a cool 60 degrees in the winter here so I have a small heater that keeps the plants in the low 70’s. I have two plants with a small circulating fan and two grow lights, one 1500 and the other 1000. My problem is I cannot slow the exhaust fan down enough to get the humidity up past 30%. I think even with a small humidifier the air exchange is too much. A 6’’ exhaust fan was basically recommended for my tent size, what are the thoughts of the group on this
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@traveler05 If you have small timer you can set fan to kick on and off to adjust fan the heater is probably whats causing the humidity problems
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I would first try to cycle the exhaust fan by temperature or humidity, or timer cycles. If the exhaust fan stops the transpiration of the plants will bring up the humidity in the tent. I would try to run the exhaust fan at least 10-15 minutes per hour. Longer or shorter durations won’t matter as long you maintain at least a 20-25% run time.
Your lung room must be at a humidity lower than the 30% in the tent. You may end up adding humidity to the lung room, when the fan cycle time becomes greater than 50%. With constant ventilation through the tent, it will be best to control the lung room conditions.
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The AC infinity humidifier is awesome it is adjustable to amount of out put you need. 15l capacity or you can get smaller but it with put out like a fog machine. Also comes with a 69 controller that will accept control for many devices, fans, lights and humidifier. Check it out. Good luck happy growing!
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Thank you all for the input, a timer might just be my first try, I’ll post results.
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What exactly are you running for light? Because there is no such thing as a 1,500 watt light. Having correct lighting (approximately 200 plug watts per plant) is necessary.
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The AC Infinity humidifier is a great unit, and comes with a remote humidity sensor and discharge tube that will allow it to be placed outside the tent. I prefer the AC Infinity #79 or #75 smart outlet controllers, and let the humidity control itself to the desired set point. Then use the outlet controller to cycle the exhaust fan by humidity or temperature. Also can use it to control heaters or dehumidifier also, for $70. As far as the humidity goes when there is a tent full of plants your need for humidity will go down. In my 5x5 with four large plants in coco with continuous ventilation the humidity is 15% above the lung room. The coco gives up a lot more humidity than I like. So playing around with a timer first may give a good starting point.
Here is screenshot from the controller history last night. It is cycling the intake and exhaust fans to hold the humidity between 45-55%.
Then a screenshot of morning startup, and after the light is on causing plants and coco to give up humidity. The humidity will not drop below the 45% cut off point. The result is a daytime lung room temperature of 65 and humidity of 45%. The tent runs 74 degrees, and a humidity between 55-60%, with continuous ventilation. Also the controller gives you the ability to monitor conditions, and make set point changes from anywhere in the house with Bluetooth. This is great also.
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You might try hanging a small towel with the bottom in a bucket of water adjacent to the air intake. It will wick up the water as it drys out. If that doesn’t work add a humidifier to the setup. If that doesn’t work put your exhaust fan on a timer. The timer is a last ditch effort because I think the fresh air is very important for your plants.
Add a few ounces of H2O2 to your water bucket to keep any microbes from brewing up.
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Unless you have a tent full of plants. There is absolutely nothing wrong with playing around with a timer in order to get an idea of how much humidity demand you have. If you have some idea of a timeline that it takes to increase the humidity by 10%. You will have a much better idea of how much humidity you will need. One can go to some charts and look up how much water weight is in a cubic foot of air at certain humidity. Then run the math in order to know exactly how much water is needed. But again, your tent’s needs change so much from seedlings to harvest, I find it best to size equipment with an educated guess first, and use the trial and error method.
A bucket with a towel is not going to do nothing in a 4x4, unless you rig the towel on a rack with a strong fan to blow through it. I would just buy the small AC Infinity humidifier for $49 before wasting my time going down that bucket and towel rabbit hole.
Thats what i need right there. Thanks for sharing.
Go online and check how the how to use video, I could not believe the moister that puts out. It’s a trip. Thanks
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Wow lots to digest here. My lights are Abriselux 1000 and 1500. I’m just starting indoor growing and trying to start out on a budget and learn as I go, as it’s only for my consumption so I’m not real elaborate yet. Thank you all for the valuable input.
So your lights are 150 and 100 watts respectively. You might be able to run two plants with that amount of light. Adding more to your grow space will: increase temps, increase transpiration rate of plants (humidity increase) and ultimately increase yields. Low light will at best produce loose airy flower with low yields. Worst case; low nutrient uptake with leggy, slow growing plants. Rather than spend money on a humidifier I would apply that money to improving lighting.
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What is the RH of the basement?
If it’s much higher then 30%, then I wonder is the senser in then tent in the direct path of the circulating fan?
If this is all true, the reading of 30% may not be an accurate representation of RH in the tent.
If the RH is not much over 30% in the basement then added a heated humidifier would help raise temp and RH.
Lighting has been an issue with me as there are so many opinions and choices. What would be my best bet for lighting, without spending a small fortune as I have stated I’m not a commercial grower, just a beginner on a learning curve.
If you’re being affected by the real cold temps up northeast the outside RH is way low and your humidifier can’t keep up is my guess.
I hooked up a second humidifier the other day to help keep up with changes
Built it using house of hydro kit 5 disc set up and 5 gallon bucket etc.
They work great in my 4x8x7 tents
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Yup, definitely the situation up here. Forced air furnace running more than normal with the low temps, drying out the house even more.
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@Skydiver, I was just wondering about something like that. I’d heard people on here make mention of homemade humidifiers but never investigated. The one I’m using now is not big enough for a outside building. I’ll check them out. Thanks!
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I have their 6 disc unit too but kept having issues with them losing their mist making and after 4 replacement units sent to me at no cost I gave up on them and went back to 5 disc models. They had an issue with manufacturing and that was 3 years ago and may have solved that issue I’m not sure.
I use an inkbird controller that I have a power strip plugged into and on that power strip is 2 double plug timers that are set to be off just after lights out and come on just before lights one.
So both 5 disc units come on at same time when humidity drops one % below setting and run until % reached. Keeps my RH within 2-3% of target. With about 8-9 gallons water when full lasting 24 hours between refill even now with cold outside temps even longer when it’s not so cold.
Much easier than when I had 2 or 3 regular humidifiers inside tent where they would not maintain % and go to low or too high.
This is soo much easier.
You’ll see the dips is when lights go off for 6 hours.
Past week view
Today
Running 2 units using power strip which powers on/off by inkbird
Timers are there because of temp drop when lights out and don’t want to maintain say 68% humidity when temps drop 10 degrees
Hope this helps
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