CO2 Generator/Injection

[hippie420]

Hey guys thought this was a very good one for the small space grower wanting to feel the large grow system love. Even one for the Micro Cab guys.

Author:superpedro ICMag

Hi!
This is a system that enables you to use CO2 application without a big cost.

The system I'm building now is to replace the bottled CO2 I'm currently using in my small cab.(link in my signature), with CO2 brewed from sugar, yeast, and water.

The dosage system is made of an submersed container, that enables water to exit the container at the bottom. The hose from the “brewery” is connected with a T-piece to the CO2 container under water, and the other end to the electronic valve.
You need to calculate the size of your cab., and the CO2 amount needed to raise the level to 1500ppm (1,14L of CO2 for each m3). Then you build the submersed container in the exact size for the amount needed.
The sugar to water ratio is 100g pr. L, and no more than a fingernail of yeast is needed to start the production. This mix delivers about 20L of CO2 over a ten day period.
A good idea is to have two half size cans for the brewery, and replace one each 5 days for the most steady flow.
You set up the brewery size, so that the container gets filled within the amount of time, you have between your air replacements, and you should oversize it. Excess CO2 will leave the system through the bottom of your container and wont make you overshoot your target level. You can keep the container outside the cab., or fit a lid with a exhaust hose.
Start the mix a day before connecting them to the system, it takes some hours to get going.
The e-valve is controlled by a digital timer with one minute intervals, and the ventilation of the cabs on another one, set to exchange the air prior to release.



The system was scaled for a 25m3 room with a 600W hps running in a closet that exchanged air from the room. It used 100L yeast mix for 5 replacements of the room during each 12 hour light cycle.

The old big cab.

Later in that same system, I tried using 2 floating switches in the CO2 chamber, to control the start of the fans when the system was almost full, and the second switch was fitted with a delayed off mode, that kept the e-valve open for 2 minutes for the CO2 to escape. That way I got to use all my CO2.

[hippie420]

The system I'm building now that holds 1,3L of CO2 for my small cab.:

Materials:

I use an air hose connector from an aquarium store to fit the CO2 line from the container:

The finished product, there is a small gap between the CO2 container and the bottom of the aquarium. (I'll ad a few pics when it is up and running)

Since my new cab is a micro(less air for each plant = you either need frequent exchanges, or a constant addition), I've added an extra feature, with at needle valve bypassing the e-valve, to make a constant flow equal to the consumption of the plants. I'm going to adjust the flow by making a measurement of the CO2 level prior to the exchange cycle(hand held devices for indoor climate measurements can be leased for a few days where I live) and then adjust the valve to add just a bit more than the used amount in between the cycle.
I need an extra e-valve for night shut-off.

BTW, the reason I want the water column above the CO2 container to be so many times taller than the container itself, is to have an almost steady pressure for the release.

Hope you like it!

[hippie420]

It is not controlled by an expensive dosage device.
I simply calculate the amount needed to raise from 360ppm to 1500ppm, and inject that amount after the air in the cab has been exchanged with outside air.
The amount injected in between the air exchange cycle (2 hours in my cap), is adjusted with the small needle valve, and set by a single measurement at a time when the cab is full of fast growing plants.
The air exchange and co2 injection is done in 2 minutes in my small cab, and whit that, the ppm level is reset to 1500ppm every 2 hours.
My goal is to stay within +/-100ppm.
It could be used as an bio alternative for bottled gas with a CAP device.

Thanks guys
@foomar: That sounds good, I'd like to know how it works out for you.

Here is a picture of the simple injection system setup. 1,3L of CO2 releases in 8 seconds:

When running a microcab like mine, I would recommend to add the slow release in between the exchange, or a rapid exchange cycle.
In a large setup with plenty of air for each plant, the CO2 level won't drop as fast, and you should be able to stay within the desired range when using the right air exchange frequency.

BTW, adding salt to the water in the aquarium makes it a better barrier, otherwise a tiny amount does diffuse through the water. And I won't recommend using plastic tubs with soft sides for the build. Thats why I have a wooden frame around the first one.

The first full run of the system will be included in my grow thread.

Cheers!

Quote:
Originally Posted by whatissixbynine
could you explain better the flow ? especially the valve bit, not quite 'seeing it'
Hope this helps.

1: Night shutter valve.
2: Valve for timed dump of all CO2 collected.
3: Manuel valve enables a slow flow, in order to stay close to the target ppm until next dump.

@Lazy, sorry haven't read your post until now.
I used a tester from my work in my last grow, but only for a day in early flower to get the "slow release valve" adjusted.
The release dump makes the 1500ppm near perfect.