hey guys, i was searching on the net for help my with my issue with no luck and stumbled across this website I saw forums of people asking for help and getting advice from other members so hopefully i'm writing this in the right place If anyone takes there time to read and answer my post with a tip to help my issue i'll happily buy that person an itunes or amazon voucher or anything similar to show my appreciation To help i'll explain my setup then the issue i'm having, also if I've posted this in the wrong place please let me know Right, my set up is a small grow tent with 4 plants under a 600. I have the charcoal filter at the top with the extraction fan set on high and the exhaust pumped up into the ceiling through four inch ducting. I have an oscillating fan (normal household size) but with the stand removed, lying face down on the ground in between the 4 plants, not oscillating obviously... And for fresh air coming in iv always just relied on the air vents at the bottom of the tent. The ducting from the exhaust blows out allot of air so since the amount going out will be the same coming in i thought this would be sweet! (if you disagree with how i have the oscillating fan here's my reason, if not skip the next paragraph) (My reason for placing the fan how i did was that i thought direct wind would increase drying of the leaves out and also i thought with no wind the plant could use its energy growing rather than strengthening stems... This is my third cycle, both other times i placed the fan normally and rotating but still had to use a steak to support the weight when in the late stage of flowering. Also using string from the steak tied to the other stems. So i saw no sense in strengthening the stems with wind, but to ensure air was circulating properly in the tent i faced it downwards..... I have three friends that grow, each with there own system, and I have read peoples theories on the net. I find when it comes to this, theres no way to get factual info online because the correct info out there is equal to the crap, Iv'e read strengthining stems allows for more nutrients to the plant. but i dont believe this, the job on the plant is to grow the best and biggest it can with the water, light and nutrients available. If a stem growing thicker made it grow better it would do it itself.... so I assumed it strengthens as a way to protect it self so it can grow with the rest of its energy.... I say this only because of the large number of ppl on line that say thick stems mean better plants... theres equal ppl disagreeing, so i used my logic to decide whats right. But apart from the logic i just explained, I dont actually know so if im wrong feel free to set me straight...) And my air setup always has worked fine. I have the tent in a room that has a permanently open window, my last pull i got 14 oz. so this is my issue, now is my third attempt but here it is almost summer and the weather is hotter, 26 deg Celsius is where i aim for, but not above 28. 15 - 28 i was tought. But then is started getting to 32!!! So I got duct tape and taped up all three air flaps at the bottom of the tent, and got 5 inch ducting running it into the circular hole at the bottom thats designed for air intake, and had it mounted right beneath my open window. (ducting length approx. one meter) I did this so all of the air coming in was fresh from outside, rather than from my spare room with an open window. (and closed curtains) And also the outside air is cool so i thought this would fix the problem! My friend suggested this. I have my light running at nght time, 8 - 8, and right now the air is cool outside and the room my tent is in is warm. The room is approx 4 x 3m, i have the exhaust pumping into the ceiling where i removed a downlight. Is it normal for the actual room to still get warm? But mainly, with me making the tent as airtight as possible, taping up flaps and placing empty pillow cases in the gaps at the top and bottom of main zip, i removed a plant, zipped myself inside the tent to check the flow of air coming in and it was only a very faint breeze.... and my temps have still been hitting 30.... i again checked the flow coming out and it blowing out strong and fast,,, so why isnt the incoming air the same or close to the same from my ducting? i know the zipps are not air tight but shouldn't air flow much easier from an open 5 inch duct? (if this makes any diff, the bottom duct comes from window, down wall and into tent..... I thought maby cause the air is being sucked from higher than where it enters, i dunno.... My leaves are turning yellowish, (not badly just pale green/yellow) and the edged of each individual leaf is curling downwards, a friend told me the reason for this was high temp causing low humidity makes the leaves do this in an attempt to trap moisture under the leaf.... Thanks ppl!! I know its a long read but i'm very new to this, last two times i was being taught how to grow but when it comes to problems i have a lot to learn!
Ok, so as I understand you're having heat and humidity issues? The pale/light green leaves sounds like a nutrient deficiency (nitrogen). What is your soil mixture? How often are you watering? You want to let the soil go dry between watering and let the roots breathe. Your curling leaves are probably from over watering/under watering or heat stress. My humidity levels in my area are running in the 30% range and are fine. Do you have A/C in your home? Your venting sounds right but I would not tape/block your passive intakes. You want cool, fresh air to be pulled into the room by the passive intakes and the warm air exhausted out. I would suggest venting out that window and keep the room as cool as you can. Use fans and blow them at the tent. Aim your fan in the tent at the bulb. The circulation will be enough for your plant. You don't want a powerful, constant wind on the plants as this can stress them. What type of reflector do you have? If your exhaust fan is on high and still having issues with heat, then there's you're huckleberry. Summer temps are more than likely the main culprit of your heat problems. A/C and keeping the room cool are your first goals. Otherwise, a 600w in your grow area during the summer may be too much. I live in AZ where it reaches 105f+ most days June-August, its very difficult to grow that time of the year here.
temps of 32c is not a problem. look elswhere for the cause of your yellowing leaves! your ballast is outside of the tent isnt it? can your fan be moved closer to your intake ducting to help draw air through? or point it up at the light instead of down at the ground try removing the pillow cases to allow some natural ventilation as well, especially at the top so the hot air at the top can flow out the top without needing to go through the ducting but 32 is not a problem. 38+ is what i consider a problem.
How far does the duct travel from the window to the tent? It sounds like it has some bends too. 5" is not that big either. Distance, bends, and diameter will cut way down on the amount of air flow through the duct. Agree on opening the flaps so you can get more air in there. A stronger exhaust fan will pull more air in. 32 is too high.