I've read all the CO2 methods - But do I need it ?

Hi all,

This is our first grow for me and my hubby, been sampling for 30 years but now we have the room to grow. We are approx 6 weeks in and I'm scared cos everything seems to be going too well. Set up (after lots of research) we thought was just satisfactory using CFLs, started with 100 watts curly ones for seedlings, then 125w dual spectrum, the increased to 200w dual spectrum. We have a dual spectrum 300w in a walk in wardrobe 5ft x 5ft for the bigger veg plants coming into pre flower, and will use the 300w and 200w together for flowering. Used J Innes no. 1 for soil mixed with Perlite. We have a pellet type fert for veg stat, and will use bloom and topmax for flowering stage. I have managed to get the walk in wardrobe temp down from 30.1 to 28.9 lights on - so relieved but would like dark temp to be lower than 24 but just cant do it, we have no machines, just two fans circulating air, using the door open method. Our plants have been unbelievable thoughout - looking at MJ growers Bible we have, could I say our babies are just about perfect! (Touching something wooden!) Lush, green, no leaf damage anywhere - one plant droops (maybe a root prob) and we have one Autoflower now flowering (this was a first test subject - easy and lazy persons plant, but good to get the feel of the stages although shorter for an AF)....Now my biggest stress is airflow/CO2 levels, as when we flower and go 12/12 I will basically have to completely seal the door gaps due to light that will then stop the little fresh air that goes in when door shut and thus may affect fressh air and CO2 levels too much. I have spent all morning, reading the war on the CO2 thread and thought 'sod' the CO2 side of things as we dont need huge yields, but will our lovely plants have enough CO2 and fresh air circulation. Still unsure what to do - any suggestions? Thanks.

hey there newbie. your going to have to figure a way for both air intake and exhaust. is venting or intake through the ceiling or floor an option? i'd be careful about adding co2 to a space near where you sleep or spend time. even mod levels of co2 are a respiratory irritant and can cause headaches if exposured for too long. good luck on solving your problems. may want to research autoflowering strains for next time. i'm not positive but i don't think they have the rigid day/night cycle that regular plants do.

Cheers for that, luckily we just have one Autoflower, left over from last batch of seeds - doing well considering a little stress at seedling stage. All the rest are just feminised, and they are the ones I'm worried about (they are just coming up to preflower stage) and are very happy at the moment. May just have to plod on, at least on 12/12 I can have the door open for longer so there will be non stale air and just risk the lack of CO2 and see what happens. I did read that Newbies should do as little as poss when learning and then gain knowledge to tweek later - good advice i think. All advice gratefully received, always .

You need fresh air/c02 in the room as plants will use all c02. during lighted hours leave door open as a house has higher c02 concentration then outside

outside of your house co2 is around 300-400ppm, inside your house 600-800ppm. i was calibrating my co2 sensor a few hours ago. in my set up I just bring fresh air/co2 from inside the house and exhaust outside. after this grow just replace your cfl with a hps with a air cooled hood.


ps plants turn co2 in to fresh air

With such a small amount of light co2 really wont do much for you. Your using a minimal of low grade lighting so no real co2 advantage. You do need to figure out air exchanges though as you will need to exhaust and then fill with fresh air from outside the room. This will help your plants yields and help prevent mold. Using those 2 bulbs together should be ok for 2 or 3 smaller plants the footprint grow area will be small maybe 2foot by 2 foot. Try to keep temps around 75-78 F with co2 you would need it 80-85 ish with co2 ppm between 1200-1500 ppm.

Save your $ and just buy decent soil and such.

Tanks of CO2 are a waste of your money until you get the plants growing correctly.

with the lights you are using , an oscillating fan should more than be enough.

Many thanks for all the advice peeps.

dadio161 - I was hoping someone would say that. I am going to risk the 'vent with open door method', i know there will be a lack of CO2 but for our first time I am going to see what effect it has........ certainly when doing 12/12 we can have the door open. £££ are scarce and dont want to go down the route of all the gizmos. Just happy to produce something, not after enormous yields and if our flowering autoflower is anything to go by I dont believe these plants are suffering too much (at the moment) with this set up, I suppose we will only know with the end product.