First Timer - Super Critical Autos From GHS


New Member
Hi, this is my first grow! I'm using a 1.2 x 1.2 x 2m tent, 600w HPS bulb. I have a 5" cooling tube and a small reflector (I have a bigger one, but it doesn't fit the cool tube, so I've just hung it above the other one to reflect the escaping light back down). I have 2 x 6" clip on fans circulating air. I have been advised that I won't need another intake fan as the size of the tent and the vents at the bottom are sufficient for air circulation?? I will have a 5" fan for removing air through a 20cm carbon filter (brand new) later on in the grow when needed. I'm growing Super Critical Autos from Greenhouse Seeds. I germinated straight into the final pots. Not sure of the size of the pots, but they seem big enough from what I've seen on here. I'm using Canna Professional Plus with a 30%-40% perlite mix. I soaked the soil before planting the seeds for 24 hours with tap water (left for 24 hours) and Canna Rhizotonic (only 5ml in 9lts) balanced to 6.5ph. Planted the seeds and covered with cling film. They all popped within 72 hours and from what I can tell, they seem to be doing OK. I watered again today, 6 days from popping through. My temps are sitting at 26-29°C in the day and dropping to 18-20 at night. Humidity is hovering about 55%. I have my light turned down to 400w and I'm running the lights and fans at 18/6. I have the thermometer placed on top of the pots and the light is about 30cms from the pots. I will put some pics up for you to have a look. Please criticise if you see any flaws in my set up, like I said this is my first grow so really would appreciate any advice or hints and tips! Thanks for taking the time to read this and I look forward to hearing for you!

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Hey Dwang, welcome to 420 Magazine! you have come to a great community of knowledgeable, friendly people and lots of great info.
The babies are looking great so far, they will thrive nicely in your grow space. Seems like you got a hold of things so far.

You shouldn't need an intake fan with your air vents at the bottom of the tent open since the exhaust fan pulling old/hot air out of the tent will actually cause negative pressure inside the tent and pull fresh air in thru the lower vents (if you close these vents the tent walls should suck in, that is how you know your tent is sealed well) If you find you need more air intake due to to much negative pressure, you can always add small computer fans to the lower air vents.

Be careful with your light being so close to the babies while they are so young. To much light can cause spots and bleaching. You should be good for now though, just letting you know. You have the air cooled hood so it shouldn't be a problem but you should also try to keep your temperature from getting higher than 26 degrees.

Another good tip would be to hook up your exhaust and fans separate from your lights, they wont need to be on a timer like your light. Exhaust and circulation fans are always good to keep running to exchange the air constantly in the grow space. If you find the room gets to cool over night because of the exhaust running you could always shut if off again or get a speed controller to turn it down some.

Hope some of this info helps out. Be sure to keep updating your journal and ask any questions you need to. More people will come in and check out your grow eventually as they keep seeing it get updated. If I can't answer your questions I will try to find someone who may be able to or there is always the FAQ section of the forum as well. Best of luck!

Having such a nightmare with temps, but think I've finally managed to keep them down a bit... anywhere from 23 to 29°C. Humidity between 35 and 70%. Toe of the plants are going well I think, one has been a slow starter so I've decided to experiment with a bit LST with this (this is my first grow and I'm probably not experienced enough to be doing it, but I'm not so bothered if I lose a plant at this stage as long as I gain experience for the next time). Can anyone tell me how much and often I should be watering these babies or should I just stick to the old weight test?
Hope you are all happy!!!

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I now have a 6" fan extracting through the carbon filter, with about 0.5m of straight ducting, a 5" fan pulling fresh air from the window, through the cool tube and out of the tent. I also have 2 x 6" clip on fans circulating air and have 2 of 3 vent flaps open... for some reason, when I have the ballast turned up to 600w, I can't get the temps below 28.5°C and more often than not, they're hitting 31C! Should I just give up on 600w and turn it down to 400w boost? Am I stressing too much about the temps?

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Hey again Dwang. I was sitting here trying to boggle my head as to why you can't get your temps to drop any. Then it finally clicked, you said you are drawing in fresh air from your window. What has the temperature outside been lately? This could be causing the temps to stay high because you are bringing in warm air while trying to get rid of it at the same time.. What is the temperature inside your house lately?? Is it cooler inside than outside? Also, what is the cfm rating for your exhaust fan?

Lets try doing this and see if it makes any difference. Take out the intake from your window all together and close that inlet to your tent.
Try to setup all of your equipment like this..

Carbon filter > reducer/short ducting > cool tube > ducting/exhaust fan > ducting out of top of tent

Now, once you have this set up, make sure all of your vents and ducting ports are closed off tightly and that your exhaust ducting is tightly secured and sealed to the 1 open duct port you need for the exhaust. Close the door as well. Turn on the exhaust fan and keep an eye on the tent walls, they should suck in due to the negative pressure in the tent. Now, open up 2 of the bottom air intake vents and the tent walls should go back to normal position.

Run the tent this way for a couple of days and see if your temperatures change any. When you bring in air from outside the house you are bringing that air temperature and humidity level into the tent which I'm thinking may not be helping your situation this time of year. Not to mention you could be bringing in a ton of airborne particles from the outside air if not filtered well. Hope this helps that issue since I have noticed some leaves curling up due to heat stress!

On to the watering of your plants.. In a couple of the latest pictures your plants seems to drooping a little, maybe it is just the one plant possibly? When you do water try not to water just around the base of the plant, if you water around the outside edges instead the roots will go searching for the water. With those size pots and the way the temps are right now I would say you will likely be feeding them plants every few days right now. The "lift the bucket" method is usually the best way to go as long as you know how light the bucket was while the soil was dry. Another thing that I have seen people do is actually weigh the buckets when dry on a bathroom scale and then water and weigh again, then when the weight drops back to dry weight you know it's time to water. Letting the soil mostly dry out during early veg will promote root growth, but don't let it dry out to the point that there is no moisture in it at all. A moisture meter can help with this to. Just always make sure that the top couple inches are getting dry before watering for sure, the lower soil could still be moist. Be sure not to overwater :) There are also some helpful threads around here that you could read up on as well to get more info.

Best of luck over there, let me know how the temperatures fair out after you change up your exhaust system.
Looking well so far;) good keep it at the 600w setting try raising ur light abit also and have ur fan between plants and the lighr that will keep ur ladies the pics they look fine just need abit of water.there gna turn into beasts in that setup;) best of luck il be watching.ul know if ur temps are to high if u see heat stress on your plants.which is not visible.dont over worry autos are very strong beans and will do u proud;). Also dick mate good work dishing out some top info.good lad;):goodjob::thumb:
Thanks beast! I try to help out where I can from what I have learned around here and from my own personal experience :)
Have also learned quite a bit from your auto topping thread, helped me figure out what to do with my first autos. Did a side by side experiment with 2 strains, 1 topped and 1 natural.. I wont go back now i don't think, will always top or fim my pants.

I thought I noticed a small amount of heat stress on a few leaves. What I seen was in picture #2 and #5, leaf edges starting to curl up some. Please correct me if I am wrong, this is normally caused from heat stress correct? That is why I went with that route of information for Dwang here :)
Dick nice to see u like the results of topping and enjoy what it brings.does make a far better plant bigger buds;) glad could be of help.and i didnt notice in the pics till i looked not doubting nowt u say mate ur bang on;) good work.;) id say raising light would resolve that issue how close is the light to the plants? And all of what u said aswell ha ha;)
Hi dick and beast! (Ha, made me chuckle)

Thank you so much for your replies and input! Where to begin...

@dick Yesterday, I spent many hours of time changing the set up round. It drove me mad, I tried 4 different ways and ended up the same as I begun! My first attempt was exactly how you described above, I left it am hour or so to settle and temps were 35! So then I added the 5" just blowing fresh air from outside into the tent (filtered for bugs etc!). At this point I had removed the cool tube and was just using my original hood (I prefer it). This didn't help, the temps were still above 31. So have reverted to my original set up. Let me clarify that the 5" fan is now pulling from the window, through the bulb and out of the tent, no air from this exhaust mixes with air inside the tent. I have 6" fan just extracting through the carbon filter at the top back corner of the tent and into my room. There have been two mesh ports open all day and the light has been on 24 hours as I need to change the dark period time to a hotter part of the day, thus helping temps. When I got in from work, the temp was at 27.0°C and humidity was 39%. Which I'm very happy with, the only downside is that the ballast is set to 400w boost, which I believe equates to about 470w (?).

As I live in the UK, and on the East Coast, there is, unfortunately no chance of the outside temp being a heating issue in the tent! It's been about 18°C today, that was amongst the heavy downpours!

When the 6" fan is on and the ports are closed, there is massive negative pressure, you can hear the fan working harder, so there's a good seal there. I bought a Black Orchid inline fan. It's 298/CFM.

@thebeast27 thanks man, I've heard good things about these super criticals, so hopefully you're right and they turn into beast's! How far away should I have the lights? I was told about 1ft?

Thanks again guys for the help and advice!


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Also, I am using a little (5ml in 10lts) of Canna Coco A&B. It is 1/4 of the recommended dosage. Are these ok to use? as it's only the start of week four, I want going to start the Canna Boost until I'd seen some flowering to start... sorry for all the questions again!!!

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Light looks good but i bet if u lift it another half foot planta will respond well.apart from that id say u have everything in hand good job.gna be some good plants for sure;)
They seem to have grown since yesterday so I'm just gonna water them then take some more pics with the light off so you can see the proper colours etc

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So I took some pics with the light off, before I watered, in hindsight, not that clever lol. There's some progress on the little one (LST experiment), you can really see her bending! Also gladly all females, which they should be! I'm not normally a lucky kind of bloke, so I don't trust much!

I've raised the light a bit and turned the fans so there on the canopy, between the light and generally pointing in an upward position to help remove heat.

Anymore tips would be greatly appreciated, looking forward to them!!


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Wow, seems strange that you are getting such hot temps this way. Your ballast isn't inside the tent is it? That would create quite a bit of heat. If not than I'm not sure what to say, maybe your light just really puts out that much heat. Unless it's the glass in the cool tube that is making things heat up so much around your plants. Either way, just keep a couple fans blowing over top of the plants like thebeast had said earlier and hopefully they don't get any more heat stress. Also raise your light up to 18-24" and see how that works for ya.
No, the ballast is outside the tent. Today seems to have been a good day for temps, so fingers crossed it stays this way!
So I took some pics with the light off, before I watered, in hindsight, not that clever lol. There's some progress on the little one (LST experiment), you can really see her bending! Also gladly all females, which they should be! I'm not normally a lucky kind of bloke, so I don't trust much!

I've raised the light a bit and turned the fans so there on the canopy, between the light and generally pointing in an upward position to help remove heat.

Anymore tips would be greatly appreciated, looking forward to them!!

Did you turn the light off or was it time for the light to go off anyways? Always leave the light on it's proper uninterrupted light schedule, if the light goes off and oon at random times it will stress the plants and they could turn hermaphrodite on you even if they are feminized seeds. I am just asking and throwing that in there just in case, for you and your plants sake.

Good that you got the fans blowing over top of the plants now, aiming them upwards was a good idea, your filter will be able to pull in the heat easier this way.

For your lst experiment, you got the right idea going there. you should also put an anchor string at the base of the stalk going the opposite way of the one you just put on, this will keep the whole plant from leaning over to the side. Since they are starting to flower though I wouldn't do to much more major training, you can still bend some branches in the direction you want but it's best to try and get all the training done before flowering.

Let me know how your temps fair out later on today or whenever you report again. Hopefully it works out for ya :)
It was due to go off. I've been on an 18/6 schedule, but selfishly had the lights to go off when we go to bed, but having struggled with temps, it makes sense for them to go off in the middle of the day when it's hottest outside. So I need to change it by about 12 hours... should I leave them on for 36 hours to get the right time to turn off again? Temp is currently 26.4°C and humidity is 42%. Happy with that
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