Co2 for Beginners:

Summary: this post will give basic instructions for augmenting Co2 to your tented plants using yeast and sugar. I currently keep 8 plants in a 5×5 tent and consistently maintain 1400-2000 ppm Co2. This method requires a remote viewable Co2 sensor. (mine is bluetooth or wifi)

Cost of running this system is variable, but sugar and yeast cost is roughly $70 a month. Beyond that to add Co2 in large bursts (like after a trim session, or watering) I keep on hand Citric Acid and Baking Soda as well. I will cover this more later. This system can be scaled back to augment an All-Tank setup to conserve the precious and spendy gas by pushing a baseline amount of Co2 while the tanks make up the difference.

Attain these items in advance:

10 1 gallon water jugs with snap seal (push-down-to-close) lids

-if you have several options, buy one of each and pick your best sealing brand

A fishtank Air-pump

Air-tubing

You will need about 15 feet plus the length to span to a warm area if your lung room is cooled

A seedling heating mat

This will be dedicated to this purpose, you may need another if you already have one

A large measuring cup

I measure 4 cups repeatedly, a one cup unit won’t cut it

A funnel that fits your gallon jug mouth

Glue

This glue should dry rubbery like rubber cement, or if you have to, silicone

Air tubing connectors

I bought a cheap pack option on amazon and really needed them (currently using 5 elbows and 3 tees)

Power at your heat pad/jugs location

You may need an extension cord (2 plugs needed here, heat pad and air pump)

An Awl

This is a tool, like an icepick with a progressively larger shaft from the point away….
This is needed to MELT precise holes in the lids
Do Not Attempt with a random screwdriver

Thermometer

An infrared point and shoot thermometer is nice

A heat source to melt lids with Awl

A stove will do, i prefer a handheld torch

Sugar

You will be buying this often, 8 Lbs lasts me 5-7 days
Try starting with 40ish pounds

Yeast – 1lb per month of the grow

I use Distillers Active Dry Yeast, this is for high alcohol production and perfect for a sugar wash
Amazon sells a 5 one pound packs for like $45

OPTIONAL LIST OF GOODS

Baking soda (sodium bi-carbonate) 2 carbon atoms for your ladies

Lots of baking soda
Amazon sells a 12 one pound case for $11
I use 12-24 pounds per grow

Citric Acid

This stuff is expensive, my last purchase of a 10 lb pail was $39 and i shopped around

2 small containers of equal size to store these ingredients near your tent

 

 

Directions:

The following directions are for a 5×5 tent (25 sq feet) and you will need to size up or down the overall jugs and or yeast to balance your system

Making Sugar Water

1.  measure 7-8 cups of water and add to a large pot on stove

2. Find a container that holds 4 cups of sugar and note on it the line where 4 cups is

Gas station big-gulp is big enough
3. Prepare 4 cups of sugar and heat your water

4. Stir sugar into heated water, it does not need to boil

5. When dissolved, transfer the pot to the kitchen sink to cool

You can pre-fill the sink with cold water to help
6. Add 4 cups of cold water to the mix now to adjust total mixture and cool at the same time

7. When at 90 degrees F or less, add 2 tablespoons of baking soda

This keeps ph (acid) from building as fast
8. Use your handy measuring cup as a scoop and funnel-transfer the pot of sugar water to a gallon jug.

There should be room on top, we will be using this

Repeat 1-8 Three More Times for a total of 4 gallon jugs

 

 

Step 2 prepare the Co2 Delivery system:

Again for a 5×5 tent

Pour out 5 gallons of water and save the lids
MELT 2 smaller than tubing holes in each gallon jug lid
Cut 5      6-8 inch pieces of air tubing
Now, cut the tubing pieces in half on a 45 degree angle to give you 10 pieces with a sharp end and a flat end
Pull tubing through the lids and leave a considerable amount sticking through the top
Be sure not to tear the plastic lid here or you will need more lids
Needle Nose pliers are helpful here
Glue the tubing to seal it
From underneath, smear the glue without compromising the seal for the jug to seal the tubing permanently
Extra time spent here is not wasted
When the glue is dry, add a tubing connector to the top of the lid’s new hoses ( I use two 90 elbows here)
Congratulations, your jugs are now ready

 

Step 3- Prepare The Co2 Jug Home Location:

 

Set heating mat on the floor in a reasonably dark location (not in the tent as the light will kill the yeast)
Set temp between 80F and 90F
In time you will be able to manipulate the heat mat to alter your output by a small amount
Set your 5 jugs on the mat as best as the fit can be
Set air pump up and run air line to your first jug
Run tubing between the jugs
-1-2 feet long to allow moving of the jugs

Last hole open leads to the tent
Run air line to the tent with a few extra feet to play with
Congratulations, this step is complete

 

Blooming Yeast and Preparing Final Solution

Create 97F degree water in 2 Quart jars or equivalent
Add 2-3ish teaspoons of sugar to the water
Add 30 grams of yeast per quart jar and stir 10-15 minutes (water should now be at target of 95F)
Repeating: STIR 10-15 minutes
This step is crucial as the stir keeps oxygenated, and the time brings the yeast to life
More yeast equals more Co2 but less time overall on your jugs
As the plants grow, the total yeast added is increased
Funnel pour yeast evenly into warmed (80F-90F) (in sink works) 4 gallons of sugar/water/yeast mixture made earlier.
Pre-warming the sugar mix prevents mass die off of the yeast by shocking it
Put lids on your now mostly full 4 gallons and shake-mix before next pour step
Pour into the 5 gallon jugs and bring to your heat mat area.
I like to keep the 4 other jugs  for making and storing a mix so when the old batch fails, I’m ready.
Put your hosed lids on your 5 one gallon jugs
Plug in the Fish-tank Air Pump.
The air should now pressurize the jugs, it is time to check for leaks
This is done easiest with a combination of listening to the lids, and a spray bottle for the hose holes.
To aid in finding leaks, plug your exiting hose and pressurize until you hear a leak, spray…. If no bubbles, the leak is at the jug seal, and is normal at high pressures. Also, yay, no bubbles
Run the airline into your high airflow tent
Setup monitoring equipment
Congratulations you are a prepping pro, now maintenance

 

Maintaining Co2 setup

On day 3 of running add 1 tbsp baking soda to each active gallon jug to reduce acid and keep yeast from going kamakazi in the alcohol bath it is creating.

Day 4-5 you may see a decrease in Co2 production, and there are two good options before pouring out….. 1. Add a gallon of sugar water baking soda mix. 2. Bloom more yeast and add to the 5 jugs. Or my personal favorite both by blooming yeast into the gallon, shake and distribute into 5 jugs.

Smell is your friend, your tent better have a carbon filter(your main fan is now always on mixing and scrubbing air). If you smell the booze or yeast now, its leaking from your jugs, grab the spray bottle

Beyond that, you will likely never vent your tent with this setup.

A dehumidifier small enough to fit in the tent is also crucial to this setup.

Sizing your dehumidifier: 500 square feet of rating on dehumidifier per 5 square feet of tent is the smallest you will want to go (mine runs on AC Infinity 69 Pro controller with an AC Infinity smart plug and tether)(this controller KNOWS VPD and runs my dehumidifier based on this and varies humidity based on current temperature and what the leaves “want”
Dehumidifier requirement: Auto-resume function in case of power outage is crucial if using my controller. (set the dehumidifier to always run and plug into 69 Pro)

Expect no more than 7 days per batch.

 

Co2 Bombs

Take the last gallon jug and pour it out. Save the lid
Fill 1-2 inches of water
Take 2 small containers and fill one with baking soda (carbon) and one with citric acid
These are for easy and fast pouring
Grab a funnel and a poking stick for chunks
Go near your tent and open bottom of flap
Set jug down, add funnel add baking soda (if it stops up the funnel add equal citric acid before poking through as this saves steps)
Add an equal portion of citric acid to the amount of baking soda just added WHILE Lifting the funnel. The gas will escape immediately and blow citric acid powder everywhere

This will produce large volumes of Co2 in a hurry, be sure to have your monitor on when doing this as 2000ppm and over is toxic to plants and 5000+ is dangerous to humans

Plants evolved on a planet with considerably higher Co2 than now and as such you should target 1400-1500 ppm to maximize growth.

Expect a 30% increase in root development and growth
Say goodbye to 2 month vegging cycles (30 days is sometimes too much in my tent)
You can get an upgraded light as your plants can take more
Target 35-40 for DLI in vegg,and if you keep 1400 ppm, you can really push ppfd in flower.

Good Luck And if you have success or other tips, please comment for others 🙂