Indoor Light question (is it to much?)

[Darthweeder]

Hi!

I'm new to this forum, and I just recently started with my first grow tent. I'm not sure if I was supposed to put this question here or in "new grower" forum.

This is my setup..

Ive got my tent in an attic that's not much warmer than the outside temperature. If it's 0 degrees (I'll be using Celsius) outside, my attic is like 6 degrees more.
I live in Scandinavia so the temperature are low now.

My tent is 120cm in length, 60 width and 150 height.
I've bought a 250 hps and a led (mars-hydro 48 reflector)
Humidifier
Fan (blowing on plants on a timer)
Exhaust fan
And a oil filled heater..

The heater I have because, with the humidifier, fans and the fan in the led light my temperature isn't more than 17-21 Celsius.
And that's supposed to be the night temp...

So! I got the idea of replacing the led with another 250w hps.
Because under my existing hps the plants its never below 20 degrees.

But is there any issues with 2 x 250w hps in my tent size I should know about?

At the moment NONE of the passive intakes are open, because of the cold weather and attic.

 

[Duggy]

2 x 250w would be fine in the tent.
I keep the vents closed and run the lights 24hrs to maintain temps..
Good luck..

 

[BII]

Looks like you are considering more inefficient lighting for the sake of getting the related wasted heat. I think it much better to first think in terms of insulation. Any kind of insulation, even just blankets or tarps, should help retain heat. In the extreme, put your current tent within a larger one or build the equivalent; or better seal and insulate your attic. Or run a tent air intake vent down into a heated area on a floor below.

You did not mention the most critical thing determining your tent air temperature! How is your air input/exhaust set up? Are you running your exhaust/intake fan constantly or are is it running off a thermostat (which is what you need for actual temperature control)? For example, I use a Lux WIN100 'outlet thermostat' (there are even cheaper plug-in digital thermostats now) within a tent about the same size.

 

[AutoWonders]

I have my radiator heater inside a hollowed out, wooden 2 drawer file cabinet and that is pushed up against the lower window vent. The inline fan sucks in the warm and toasties. Where do you plan on locating your radiator heater?

 

[Darthweeder]

Looks like you are considering more inefficient lighting for the sake of getting the related wasted heat. I think it much better to first think in terms of insulation. Any kind of insulation, even just blankets or tarps, should help retain heat. In the extreme, put your current tent within a larger one or build the equivalent; or better seal and insulate your attic. Or run a tent air intake vent down into a heated area on a floor below.

You did not mention the most critical thing determining your tent air temperature! How is your air input/exhaust set up? Are you running your exhaust/intake fan constantly or are is it running off a thermostat (which is what you need for actual temperature control)? For example, I use a Lux WIN100 'outlet thermostat' (there are even cheaper plug-in digital thermostats now) within a tent about the same size.

Insulation or getting hot air from another room isn't a possibility.

Well.. The intakes are "closed" as in I haven't opened them up but they must be leaking a bit otherwise the temperature should be higher.

The exhaust is this one

Amazon product ASIN B004WY1VBC
Set to run on the lowest setting, constantly running.

Changing the exhaust fan speed could actually solve the problem.
Not sure if that's what you meant?

I have my radiator heater inside a hollowed out, wooden 2 drawer file cabinet and that is pushed up against the lower window vent. The inline fan sucks in the warm and toasties. Where do you plan on locating your radiator heater?

I have the heater, a small 500w set to about 150w (thermostat) inside the tent and it's taking up and wasting space..

Feels like changing the light to 250w hps would solve everything.

2 x 250w would be fine in the tent.
I keep the vents closed and run the lights 24hrs to maintain temps..
Good luck..

Yup, I had to change the light to 24/0 a couple of days ago to maintain better conditions.

 

[BII]

So, you run your exhaust fan on "lowest setting, constantly running". But you have your tent air intakes closed. It is the air flow, in intake of fresh cooler air (that you've blocked), you want to try to use to control the tent air temperature.

I meant that you put your exhaust/intake fan, not the heater, on thermostat control. Simply let the exhaust/intake fan come on, suck in fresh cold air, when the tent temperature hits the upper limit you set. Or with such a high temperature difference between air temperatures inside and outside the tent, if you just opened lower and upper vents you'd get good convection, chimney-like air movement. That is, if you opened vents, you could probably limit the air flow better, and you may not need to run an exhaust fan at all, especially since you do not mention filtering your exhaust.

 

[Darthweeder]

I got a carbon filter also attaches to the exhaust.
Yeah I've thought about turning exhaust off and just opening up the holes where I got the cords to the lights and so on going out. But then I run the risk of letting unwanted insects or what not going in.
And when it starts to bloom the smell will be going out.

But yes, that would probably be the easiest and effective solution.

Edit*
I'm gonna try passive airflow. Opening up at the bottom and the top. If it gets to hot I could put the exhaust on a digital timer. Putting the exhaust to a termostat sounds like a hassle and be expensive. I might be wrong?

I'm trying out the temps today.
The plants are nowhere near flowering and when they start flowering, the smell might not be that much of a problem.
I do have neighbors (townhouse) but there's no connecting airvents. Not even to the outside, well except some passive air flow as it is cold in the attic and we do get the occasional bee in there.

This might be ok!

 

[Darthweeder]

So just checked the tent and opening up and turning fan off did not work at all.
I bumped the humidity up like 20% but the temperature stayed the same.

So I think I HAVE to exchange the led to a hps..

The led will still be useful when summer comes though.

 

[Hippy_BiotabsF70]

I was just about to say I don't think the fan is your issue. It's your cold loft! I am in a similar situation in a cold room, and I don't ever use an extractor. Just passive ventilation. It's still bloody freezing! I had to stick a oil rad in there and set it on fairly low to keep soil level temps at around 73 degrees. Cobs on 24/0 keeps the air/canopy warm just enough.

I think your 2nd HPS is a good idea mate. Not sure how much less efficient it is compared to a Mars either? It will def kick out the heat you need and give you more total light. Win win in my mind.

 

[Darthweeder]

I was just about to say I don't think the fan is your issue. It's your cold loft! I am in a similar situation in a cold room, and I don't ever use an extractor. Just passive ventilation. It's still bloody freezing! I had to stick a oil rad in there and set it on fairly low to keep soil level temps at around 73 degrees. Cobs on 24/0 keeps the air/canopy warm just enough.

I think your 2nd HPS is a good idea mate. Not sure how much less efficient it is compared to a Mars either? It will def kick out the heat you need and give you more total light. Win win in my mind.

Yeah I had the oil radiator during the night and although it did work, it doesn't feel safe and it takes valuable space.

The humidity was perfect when I turned off the exhaust and opened up down and up. I ended on like 50+% under the hps and 60+% under the led.
The temperature was something like 22-23 under hps and only 17-18 under the led..
So another hps should definitely be enough.

The walls were wet, not sure if that could be a issue?
I only tried for like 2 hours. So I was thinking about maybe making the exhaust vent out for 10-15 min every 2 hours.