Hi, I've done a lot of reading about other people's set ups - and so I have an idea as to where this might be going wrong, but I'd like to see if anybody could help point me in the right direction with regards to this specific set-up... My issue is that the temps are still too hot (settling between 28 and 29 degrees C) with the lights running in the evening (between 6pm and 12pm for the 18/4 period). This is in the UK - and outdoor temps in the evening have been around 5 degrees. The tent has negative pressure - and with the lights off has been resting between 17 and 19 degrees C. With the stealth set-up, it is limited as to where ducting can run without bends. (edit update Location is in the cellar! Equipment wise, there's a 600w HPS in a 1.2 x 1.2 x 2m mylar tent. 5" exhaust fan (in the tent) pulling through a carbon filter (a 12" piece of aluminium ducting between the carbon filter & fan - this part is all in almost straight line), then about 10ft of acoustic ducting leading out of the tent towards a vent that goes outside (the acoustic ducting has 2 x 90 degree bends in it, which are unavoidable giving the location & ducting holes in the tent, however I have managed to stop these from directing downwards so that the warm air is rising). I've also got a 4" intake fan at the bottom of the tent with around 3 metres of aluminium ducting running away from the tent with 2 x 90 degree bends in it and a bug shield on the end. Lastly, I have a 6" oscillating fan beside the intake fan to distribute the cool air that comes in. I'm wondering would it be an improvement for me to cut the 3 metres of ducting for the 4" intake fan to literally just be about 10" or so hanging out the back of the tent? There is a wall behind the tent though and this leaves only a small amount of space - so I'm concerned that it may get too hot in that location. I could obviously try it and see, but I'd like to hear people's advice before I go ahead and cut the ducting short. Alternatively, I could stretch the ducting further to a second vent (this is less stealth, so not as ideal), but I am concerned that the airflow feels quite weak and I'm wondering if this is because the ducting is too long. I can't afford to get any other equipment yet (cooltubes, A/C units etc) - so trying to work with what I've got! I'm expecting temps to come down in the UK in the next month anyway, but could do with starting the grow off so that I can time the harvest before next landlord visit! Thanks in advance for reading. Attached a couple of photos. ( will be growing tomatoes of course, as I'm in the UK... ) [UPDATE: Sorry, intake fan is 5" not 4"! I've also reduced the length of the intake ducting and it's being routed through an ice-cooled cooler bag, which I will test temps on tonight. Also considering extending the ducting from the other side of the cooler bag to the wall vent (to let cool air passively come in to the cool bag, where it will be cooled by the ice and sucked into the tent hopefully). If it works I'll post pics and update...]
It's always best to run your ducting with the least number of bends possible, of course, and the less length you can manage the better...but the main point is to get that heat out of there no matter what you have to do. You can kill a batch really quick by letting heat get to them, so it's super important that you get it taken care of. We have bends in our ducting and, all in all, I guess we're stringing out 10 yards of the stuff from where our intake is to where we vent out at...running over 2 cool tube 1000 watt hps lights. We have 2 more that we're going to install next week so we can flower with 4, but heat has been an issue with us since the very beginning. We ended up having to install a small window unit air conditioner to handle it while the lights run at night during flower. Just so happens that the room we're using is the hottest room in the house in the summer and the coldest in the winter...but it works for growing MJ. LOL Just do what you have to do right now and upgrade as you can. I don't like those grow tents for that very reason. Of course, any super confined space is going to give you problems with heat, but you definitely need to come up with the money to get yourself a cool tube if you're going to use hps. Some of the grow stores will give you a decent price on a trade in when you buy another light from them. You can pick up a good magnetic core ballast and cool tube reflector and bulb pretty reasonably price wise. And don't skimp out on your lights. What that plant will harvest out at depends on it's health and how much light it gets, so the more the better. Good luck! TWW
You could just try removing all the ducting. If you're worried about the smell for any reason check to see how bad the smell is currently. If it's a newer grow for any reason it probably wont smell much for a few weeks. I would probably try to MacGyver a milk crate/other large enough breathable container spoof that could fit around your exhaust. Btw a spoof is a toilet paper roll filled with laundry fabric softener sheets smokers use to conceal the smell of marijuana with while smoking. You take a hit then when ready to exhale you blow the smoke through the fabric softener filled toilet paper roll and the smoke comes out smelling like the fabric softener sheets.
Agreed - although I can't afford one yet, so trying to look for temporary cheap-fix solutions to get me started. Yes, I'll need a cool tube at some point. Trying to work with the equipment that I've got at the moment though. I've seen a number of solutions that involve buying more equipment, but I'm trying to find creative ways to cool the air down without buying anything else just yet. I'm a bit confused as to why my tent is still so hot that it needs a cool tube - even though I understand the purpose. I bought the majority of the equipment as a 'kit', and considering that it's located in the coolest room of the house (cellar), with negative pressure and insulated ducting leading straight outside through the vent - I'm gobsmacked that heat is still surrounding the tent and therefore being sucked back in by the intake. I've created a contraption out of a cooler bag today. Going to test it tonight - if it works I'll put pics up... I've reduced the length of the intake ducting and made it route through a 'picnic' cooler bag, which I intend to fill with plastic containers of frozen water tonight and I'll see if it cools the air down at all. I'll also find out how often I need to change the ice too!
You have a 5" exhaust and a 4" intake? That right there is a huge bottleneck in airflow, even with the intake being a fan, it's still competing against a 5" inline fan. I believe your tent is just begging to breath, and having a passive intake that's double/triple the exhaust in size would help tremendously.
Sorry, I've made a mistake - my intake is 5" too. For some reason I thought it was 4" - but I've just spotted the difference when getting this link: http://www.hydroponics.co.uk/bay6-1-2m-tent-bundle... (that's the kit I bought). So are you saying that it would be better to basically not have an active intake fan, and to simply let the exhaust pull air through the intake ducting via tent pressure - or get a bigger active intake fan?
I'd first try adding another intake opening and see what happens. The goal will be to free up your exhaust fan to operate at max potential without any drag from your smaller intake. The intake fan isn't a problem, but you don't need it if you have the correct size passive intake to match your exhaust fan (6" exhaust fan you'd want 12"+ intake etc.). Hope this helps.
Thanks, I appreciate your advice I suppose my main concern at the moment is that the room that the tent is in is warm. It's in the cellar, which is cold when the lights are off. Even though I'm routing the hot air straight through insulated ducting to the outside vent, the room is filled with warm air during lights on. Is this naturally expected due to the tent itself being warm (and therefore warming the air up?). I've checked my ducting and tent for air leaks and can't feel anything, but the walls of the tent itself do feel warm. I'm going to add another intake opening as you've suggested - and will have to pull air from another outside vent in. Does the warm air in the room due to the tent being warm sound normal? Sorry if that's a stupid question! I suppose I was just expecting all warm air to be sucked through the exhaust - and didn't expect the tent itself to warm up the room.
Depends on the material of the tent i'd say. Heat can radiate out of certain materials better than others. Unless you wrapped it up like a icebox I think it will always heat up the surrounding air.
Still having issues this morning with temporary solutions that I've tried so far. Ice cooler doesn't seem to be cooling it by more than .5 of a degree (top of canopy area has been between 31 and 32.9 C). Secondary passive intake ducting hasn't done much yet either - tried in two different places (coming in from side pointing near the light - and coming in from the top pointing downwards). Photos attached to show set-up a bit better (you'll see the bends in the ducting that I have to have, the cool box and the inside). Looks like I'm in for a trip to the store to see what else they can suggest until I can afford a cool tube and additional fan :/ Any other cheap suggestions would be much appreciated
the fan on the stool blowing cold air the bigger the better im growing in uk to and my best bet was an led light they produce little to no heat and i run 20hours a day and can sit at 25 26.5 at most
Thanks mate. Yes I'd like to try LEDs at some point. Most of this equipment came in a budget kit from Holland Hydroponics - I know you get what you pay for, but was expecting that it would at least 'work' at OK growing temps without needing to replace loads of it :/ So the more the merrier with circulation fans too? I could get an extra one and stick it in there.
Just added this big tower fan in there (photo), oscillating on full blast. It's knocked the temps down a few degrees - but is still settling at 32.6 C. Another question - if I was to get a air cooled reflector, but couldn't afford a second extraction fan yet - would it still reduce temps to run: Carbon Filter > Fan > Air Cooled Reflector > Ducting to outside vent. I know that it's better to have 2 fans (one for the carbon filter - and a dedicated airflow stream through the air cooled reflector), but as a temp measure, does anybody run it without 2 fans?
XI have two clip fans in my 3*3 tent. One is pointed directly at my hps bulb to help cool it and the other is just for air circulation. Your exhaust fan might not be powerful enough? It's best to get a fan twice as powerful as you think you need then power it down with a speed controller. That way you have extra power when you need it and a big fan at half speed of quieter than a small fan at full speed. Your best bet might be too get an air cooled hood. They really do make a huge difference. You can get one fairly inexpensive on eBay or amazon.
Hi, yes I have a 5" inline fan pulling through the carbon filter to exhaust. Just been back to check on it - and it's raised again to 34 C. This is with: 5" inline exhaust. 5" active intake fan. 5" passive intake ducting. 6" oscillating desktop fan. 1mtr tall oscillating tower fan. All on full blast, with the exhaust venting outside and the passive intake venting from outside!