Newbie heat issue

Hi all

Having problems with heat in my tent since switching to 12/12 and moving up to a 600W sodium bulb. Temperatures are running at 87-90 F (31-33 C) at the hottest time. I would like to have them on from 9pm but due to kids being around I have to do the watering and pumping out at 5pm while they are still out, so my lights are on from 5.

I have two fans in the tent, a large-ish oscillating desk fan sitting right in front of the inlet duct and a smaller clip fan clipped to the waste tray in the middle of the four plants blowing upwards.

I need to shorten the inlet and outlet ducting to make it easier for my cheapo fan, but I don't know if that is going to do the job, and we are not even into the height of summer yet - and the plants are going to get bigger so it's gonna get hotter in there!

I guess it cools down in there overnight - I am going to look in on them about 1am tonight to see what the temp is like.

So my questions for the experts are:

1) Currently I have a 6 foot duct taped just underneath an open window as a passive intake. Would it be better to instead have a shorter duct (just big enough to work as a light trap) and take air in from the (rather warm) room, or is it worth the extra strain on the fan to draw from the window?

2) Short of cutting down the exhaust duct (there is some excess) and buying a new, expensive fan, is there anything I can do to get temps down?

3) Is it even much of an issue to have such high temps if the temps then drop after 4 or 5 hours to a more acceptable level?

4) I assume humidity will drop if I get airflow sorted, is that correct? Currently running about 55%, I think that is too high, is it?

Thanks in advance. Any advice welcome.

hi, first thing id do is get an actual exhaust fan, this will help with two things, temp/humidity and fresh air, your passive intake wont be working very well because you need air to be pulled out of your tent, what size tent have you? fans arnt all expensive you can even jerry rig a bathroom extractor fan, you don't mention filter? is odour a issue?, humidity is ideally under 50 for flowering, the lower the better, hence the need for a good exhaust, as yourplants drink more in flower they transpire more in heat this raises humidty and opens you up for mould etc there are allways good ideas for penny saving in the diy section, environment is key especialy for flowering don't want to stress em to much

cozz said it all. Sounds like you need good exhaust to pull in the cooler air and get rid of the hot stuff.

Thanks folks.

I do have an exhaust fan, but its both weak and noisy! Buying a better one costs the same as an oz, so it pains me to have to do so!

Oh and it's a 120cm square x 2m tall tent.

I should also point out that noise is a big issue. Last night I could hear the little clip fan through the ceiling, making a rumbling noise. I'm going to try and lift the tent up onto some celotex today to try and knock the noise down a bit.

jump offa dat wallet
buy needed equipment to provide ideal growing conditions, or wait.

It takes some capital to going. When you ponder what you pay for weed, it is pays for itself very quickly. I was struggling with shelling out $500 for a LED light. Harvesting my fourth grow on it tomorrow, she has paid for herself many times over.

Once you have your system, growing is cheap. Nutes cost nothing. Once you are cloning, you don't need to buy seeds much. Mix ur own soil and it is cheap. So biggest costs are electricity (not in my case with LED) and carbon filters.

A good fan doesn't cost that much...

GrowinDad said:

It takes some capital to going. When you ponder what you pay for weed, it is pays for itself very quickly. I was struggling with shelling out $500 for a LED light. Harvesting my fourth grow on it tomorrow, she has paid for herself many times over.

Once you have your system, growing is cheap. Nutes cost nothing. Once you are cloning, you don't need to buy seeds much. Mix ur own soil and it is cheap. So biggest costs are electricity (not in my case with LED) and carbon filters.

A good fan doesn't cost that much...

Click to expand...

I haven't found nutes to be cheap, but as someone tells me in another thread, I shouldn't have bought the PK and flower boost nutes that I have shelled out good money for

I also haven't found fans to be cheap. I'm looking at over $200 USD for a fan :S

It has to be quiet, more powerful than my current fan, and 5". Any suggestions what to go for? Currently using a Vents TT - the worst of the worst, it seems.... Had to wrap it in comforters to get anywhere near quiet running, and it's still too noisy for my liking.

FlashBabylon said:

I haven't found nutes to be cheap, but as someone tells me in another thread, I shouldn't have bought the PK and flower boost nutes that I have shelled out good money for

I also haven't found fans to be cheap. I'm looking at over $200 USD for a fan :S

It has to be quiet, more powerful than my current fan, and 5". Any suggestions what to go for? Currently using a Vents TT - the worst of the worst, it seems.... Had to wrap it in comforters to get anywhere near quiet running, and it's still too noisy for my liking.

Click to expand...

do the cfm math, and get a fan that exceeds that need. but not by much. use rubber bushings in the installation to quiet vibration. there is going to be noise, no way around that.

buy nutes that aren't named "Super Mega Bloom Bud Fuel," an' bullshit like that. seek them via farm and garden sites, or go organic and force worms to make nutes for you. cheap! only buy items from grow shops/sites you cannot get elsewhere. sorry, shop-owners

FlashBabylon said:

I haven't found nutes to be cheap, but as someone tells me in another thread, I shouldn't have bought the PK and flower boost nutes that I have shelled out good money for

I also haven't found fans to be cheap. I'm looking at over $200 USD for a fan :S

It has to be quiet, more powerful than my current fan, and 5". Any suggestions what to go for? Currently using a Vents TT - the worst of the worst, it seems.... Had to wrap it in comforters to get anywhere near quiet running, and it's still too noisy for my liking.

Click to expand...

You can get a 6 inch vortex fan for less then 200, I think I got mine for about 160-180 right around there. Where are you growing where you are having these issues? Is it your home, apartment? My jerry rigged diy fan was way louder then the vortex. A good fan and filter shouldn't cost any more then 250-300 bucks depending on the size you need. Save your self the stress and get it lined up right the first time. It is going to get hot, and it is going to stink. I don't know what you pay for an ounce or how long it will last you but get what you need and just go with out for a few weeks or whatever, you only have to do it once.

You want a high output inline duct fan, probably a 6 inch. See if there is an HTG Supply near you, or order online. They sell inline duct fans that work just fine and don't cost a lot of money. You could buy a 6" for about $100 and it is going to last for years. With these fans you'll also want a speed controller, for under $20.

Having an air-cooled reflector is more effective than trying to cool an entire room/tent.

My tent is roughly the same size. Here is what I run:
http://www.htgsupply.com/Product-GrowBright- 4in-High-Velocity-Inline-Fan

Thanks for all the helpful replies folks.

GrowinDad, I fear a fan like that would produce more noise than is "permissable" - my neighbor has a bedroom window very near the open window to my grow room. Hence my pain at having to shell out so much - silent running fans are expensive!

Nullis, I may well try a cooled reflector before I spend three times that on a new fan.

For now, I've dimmed my ballast to 400W and the temps are back under control. I've also suspended the little clip fan from the light hanger so it's no longer causing too much noise.

When I next get paid I'll grab a cooled hood and if that doesn't work then I'll get a new fan. I will also work on getting the ducting shorter and straighter this week, which will help with temps and noise I imagine.

I did buy a muffler for mine but it doesn't do much. Mine vents right into the room in which my tent sits. That room also happens to be my office. For work, I am on the phone, on speaker phone, all day long with no issues. I hear some white noise, but nothing that would freak anyone out.

My fan is attached to a wall, not hanging on bungee cords or anything which is supposed to help noise. The other side of that wall is my son's bedroom. His bed is against that wall and he sleeps on the top bunk. You can hear a little vibration but nothing bad (he actually likes it).

I would say that the noise in my office is no more than running a cheap window AC unit or a decent HEPA air cleaner.

So I wouldn't worry about it... If they ask, which they won't, tell them it is an air cleaner....

For nutes - I use Dyna Gro. I don't think I spend $50/yr on them.

Go on craigslist, you will find a nice inline fan for under $100 I got 2 6" active air fans the other day for 100 for the pair, you can find a good deal if you look and maybe bring your cost down to 1/4oz .......LOL

GrowinDad said:

I did buy a muffler for mine but it doesn't do much. Mine vents right into the room in which my tent sits. That room also happens to be my office. For work, I am on the phone, on speaker phone, all day long with no issues. I hear some white noise, but nothing that would freak anyone out.

My fan is attached to a wall, not hanging on bungee cords or anything which is supposed to help noise. The other side of that wall is my son's bedroom. His bed is against that wall and he sleeps on the top bunk. You can hear a little vibration but nothing bad (he actually likes it).

I would say that the noise in my office is no more than running a cheap window AC unit or a decent HEPA air cleaner.

So I wouldn't worry about it... If they ask, which they won't, tell them it is an air cleaner....

For nutes - I use Dyna Gro. I don't think I spend $50/yr on them.

Click to expand...

Yeah my fan is obviously a lot poorer quality than yours. WIthout two double comforters and a couple of large towels tightly bound round it, it sounds like a jet taking off even at half speed (I of course have it on full speed at the moment).

Combined with the two fans inside the tent it's a pretty noisy room already! A better, quieter, stronger fan will be a definite investment for Round #2, if I don't buy one before then that is.

PS why anyone would run an air cleaner only from 5pm to 5am is a mystery

Exhaust stays on 24-7...

GrowinDad said:

Exhaust stays on 24-7...

Click to expand...

Yeah just I knock the power down a little during the day so it's less audible. Still running and creating negative air pressure, just not on full power like at night.

Will it cause problems if I change the wattage on the dimmable ballast in accordance with the weather? For example we have just had a few days of hot weather, it is due to cool down again over the next few days. Would it be a good idea to up the wattage back to 600W while the weather is cool, or would this cause stress to the plants?

My reasoning is that the sun is not a constant brightness, some days it is hazier or cloudier than others. What do the RIU community say?