Here's the info on the DIY CO2 system I built
Well, the system is very simple, its an old bottle of apple juice, rinsed out and filled with 2 cups of sugar and with water (~75F temp) up to about 3/4 of the way. Added a packet of baker's yeast, and within an hour or two you start getting CO2. I just took a drill bit and cut a hole just small enough to make it hard to get the airline in it but large enough not block it, so its a sealed pressure fit. It goes into another smaller plastic bottle (the buble counter) of my favorite energy drink that had two holes drilled in it. This was also rinsed and filled with water about half way. The line from the apple juice bottle goes in it almost to the bottom, and the second line is only partly inserted so it stays out of the water and takes the CO2 that bubbles out to the tank. This line then has an old plastic medicine container that had yet another small hole drilled in its bottom. I put it upside down in the tank and cut a hole on the side. This hole is about 1" square and is half way top to bottom on the container. When it is upside down, it creates a small "bell" to keep the CO2 contained, and the hole on the side is about 2" from the outlet of my canister filter which keeps throwing water at it. What I get is a bell full of CO2 with a constant stream of water hitting it which creates a lot of turbulence and dissolves a lot of the CO2.
Although I could have put one of the airline control valves on the line, I didn't as the pressure would build up and cause a leak somewhere else. Anyway, it is not needed as Whatever is extra just bubbles out the bell to the top of the tank. The release of CO2 is slow and steady. I get a nice bubble every 1-2 seconds, and can definitely tell it is dissolving as there is a lot less bubbling to the top of the tank than the bubbles I see going into the bell.
I thought of taking this concept one step further and building an in-line CO2 reactor for my canister filter with parts from the hardware store. I went there last weekend and started looking at parts, putting them in the cart and adding up a total. It would have cost around $20 to make, including pvc glue and all fittings. I thought about it and then put everything back, the system I got dissolves a lot of CO2 and the only drawback is the small pill bottle in my tank which is visible and a bit out of place. I may still do this later but in the meantime I put the money to better use and ordered other supplies for my angels.
The yeast and sugar bottle produces CO2 for about two to three weeks, after which a recharge of sugar and Yeast brings it back online...
Here is a link to pics of the system. It will give you and idea of what it looks like, these pics were of what I did at first when I was trying to use fittings, and stuff. These kept falling off, so I simplified and just used friction fitted airlines at the end and kept it much simpler and thus much more reliable.
