About the Lights & Ventilation category

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I moved a post to a new topic: How important is the dark period

Lighting can I use a 150 w or 500w halogen lamp

You need to tell us for what. Cause I sure don’t have a clue.


hi guys
i need help with the lights
im new begginer

Needing some help
Can anyone tell me why this discoloration is happening on my new flowers?
Growing with LED and taking outside during the daytime hours for direct sun.
Coco and Fox Farm nuts as per directions.
Ph is at 6
18/6 light
Thanks in advance

How close is your inside light to the top of her and when you place your hand backside up do you feel heat if so I went up 1 inch and checked my nutrients to verify all is good



I am on my first grow, my plants are about 4.5 weeks since germinating the seeds. Sorry for replying to this thread, but the systems won’t let me create a thread (not sure why).

I have a 2m x 2m x2m tent, I currently have 13 plants under 2 x 600w HPS lights and intend to have them under 4 lights when they are a little bigger. The lights are about 2.5 feet above the canopy at the moment. I have 2 problems, which I assume are linked.

  1. The temp in my tent is too hot. It was fine before I put the 2nd light on, now the heat is climbing to around 30 - 32celcius. I have ventilation (an sms dual controller) with a 5 inch intake fan and an 8inch exhaust fan. The exhaust fan is working extremely hard but the intake doesnt seem to be blowing much. I have plugged the fan directly into the wall and it comes on full, but when plugged into the controller it seems to work not much better than a passive intake.

The room outside the tent is cold and the intake fan is near an open window (i put tights over the outside of the fan to stop beasties).

The air coming out of the exhaust fan feels cold, which is odd because it is up high and the tent is very warm).

I have taken the controller back to the shop and changed it for a new 1, this hasnt helped. Do I have the correct sized fans? Also I have read that maybe I should just use passive intakes (but more of them), what are your thoughts on this? I;ve tried having both vents open, so the negative pressure is quite small. How much negative pressure should there be?

I had to fit my own wires and plugs to the fans, and thought I may have used wire that was too thick (ie too much resistance) and i have changed it for thinner wire but this is no different.

The plants are in 2.5 gallon pots on the ground the sensor is canopy height as well as my 2 thermometer/hygrometers.

The ducts are quite short and not bendy.

Any suggestions as to what is wrong and how I can get the temp down. I believe it needs to be a steady 25 celcius (ish) in the day.

  1. The humidity is too low. I think this may be because the exhaust fan is working so hard. I have 2 small humidifiers on constantly. I also have oscillating fan, up high, facing toward the canopy and on low. I realise the fans may reduce the humidity but I want the plants to grow strong stems.

I have hung wet towels in the grow tent to get the humidity up, this is inefficient and makes a mess. The humidity rises and then falls again quite quickly, and water gets everywhere. Placing bowls of water in the tent doesnt seem to make a difference.

If i get the ventilation system working correctly will this sort itself out. I realise that a 2m x 2m tent is too big for these small plants but its that only space I have at the moment and the issue is that its too hot not too cold and i only have 2 lights on, surely the controller and fans should be able to handle this. I also realise that humidity ought to be less of a problem as the plants grow.

In summary

  1. Should I need passive intakes or should the intake fan just work better, and that this is basically calculated by the controller?

  2. Do I need to raise the plants off the ground, and in turn raise the sensors and thermometers?

  3. Any idea why the controller isn’t regulating the temperature correctly.

  4. Should the negative pressure be so much that the tent is sucked in very strongly, so much so that the floor is 6 inches of the ground in places, or is this a sign that something is not right?

  5. Should I turn the oscillating fan off to get the humidity up, which is the worst of 2 evils: having no air blowing on the plants to make the stems strong or the tent not being humid enough (its currently around 30-40 %)

  6. Any other suggestions for getting the humidity up?

  7. If I get the ventilation correct, will the humidity issue resolve itself?

Thanks all for your help.

1 Like

Is it ok if I have my carbon filter exhaust line loop back around into the bottom port of my tent for circulation?

Keep your ventilation system (tubes, extractor, filter) in height, your intractor can be placed at the bottom part, but in general you shouldn’t end up your air circuit in the tent, because all the air poach won’t be expulsed out of the space, which is bad!

Make sure your ventilation system is in height, that it doesn’t make too much curves with the tubes, and that the exhaust is outside the tent, at best directly in exterior in order to enjoy the freshest air to go in your tent from the intractor.

Where can I buy a grow light for my Marijuana?

You mean a light for the growing process, or a light to the whole grow?

Hey ive been growing on and off for a while now I wanted to know is a 600 watt his light good for a 31×31×71 grow tent with 2 plants?

Sorry damn auto correct I meant HPS

Hi has anyone else used a gt-lite led bulb 500 watt replacement it has a brightness of 10000 lumens in 5000k it seems to be working fine the plants haven’t missed a beat I’m still in the veg stage should I change it when I start flower

Usually 35–50W/SF is enough,your light is very powerful, maybe you need hang it further from your plants than usual. I am using Mars proII320led in tent 4x4, 48W/SF

I bought led light from www.mars-hydro.com , they have 10% discount for Canada customers this month

Thanks for your info

Hey newbie2016 did you ever get a answer to your problems and are the plants doing well. How did it turn out?

Go buy some books!