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.
Here you see the principle in action.(old video from my first try of concept)
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.
The system I'm building now that holds 1,3L of CO2 for my small cab.:
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!