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Issues lowering humidity - please help :)

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Hey guys,


I'm currently growing in a 1.5x1.5x2m grow tent with really good ventilation and running a 400w hps with cooltube. The problem is my humidity is up at 70-80% does anyone know how I can lower this to a point where I won't get bud rot or mould. ps my night time humidity is like 90% and my day time temp is about 25deg.



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Same size tent as myself, same issues. Here's what I did, firstly, can you set up another space for veg or clones, because the heat that room produces is what you will need. Run an exhaust duct from the veg room into the tent, at the lowest entry point, and leave it running. Synch the lights to switch on so that when its night in the tent, its day in the veg room. I only recommend doing this through the cooler months, during summer, run the lights at night together. By introducing warm air into your tent, you dry out the environment. Most importantly though, is outside the tent. If you are not exhausting the air from the tent out a window or into the roof, then you are just going to recycle what comes out of the tent, straight back into it. And the entire room, not just the tent, will feel just like a sauna. Here is some pics to give you an idea of what I have done:-) hope they help.post-50453-0-27534500-1366770022_thumb.jpgpost-50453-0-63906000-1366770069_thumb.jpgpost-50453-0-23738800-1366770105_thumb.jpgpost-50453-0-05048300-1366770136_thumb.jpg Investing in a thermal controller for the tents exhaust fan is also recommended, set at 25 and bobs your uncle.post-50453-0-23605900-1366770275_thumb.jpg
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I have a 6" exhaust fan drawing air from inside the tent and then running it through the cooltube and outside. I have a passive intake also. I have a large oscillating fan and keep all the fans and exhaust running 24/7. It's not possible to run another room or pull air from another source :( Edited by censorthis
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What is the humidity of the air you are drawing in ??

 More airflow wont reduce humidity if the air you are drawing in is already 70% +  . This is the problem i have .


 I got a dehumidifier this year  to help sort the issue . Did a test run last nigh after lights come on .

Outside humidity was  75% ,inside the tent was 85% humidity . I ran the dehumidifier for about 2 hours and humidity got down 60% and it had drawn out about almost 1lt of moisture. The humidity of the air i was drawing was still 70-75% so i was pretty happy , the 2-3 hrs running reduced it about 15-20 % . I think if i ran it 24/7 it would get below 50%  .

 Nothing passive will draw that amount of moisture out !!

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Okay, try running air into the cool tube from outside, but let it flow into the tent,and set up an exhaust fan to start one hour after lights come one, and to switch off one hour after lights out. Incorporating the use of a thermal controller on the exhaust fan is a better option though. Using the heat from your light will help dry out the air, the wattage you are using won't cause enough heat to roast your babies, I have the same in the wardrobe. Just try to keep the area outside of the tent cool, I found the only way was to run a duct into the ceiling, out the window, unless you have awesome filtration, tends to generate interest from the other side of the fence!
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