After all of the "basics" type of information I've presented in the past several issues, it's now time for a construction article. Over the next two months I'll discuss CO2 generation and injection systems.
As I mentioned last month, CO2 generation systems can range in complexity from simple yeast and sugar water generators to as complex as compressed CO2 tanks with electronically controlled flow solenoids. Unfortunately, the cash outlay for the latter, more complex system, is quite high - generally in the order of several hundred dollars! This is a lot of money to invest in a system, especially if you've never seen the benefits of CO2 injection.
To overcome this investment barrier, I'll present the simple yeast and sugar water solution. It may not be as elegant and as maintenance free as a high-tech system, but then I think most of us entered into this hobby not just because we like fish, but also because we like to tinker with aquarium gadgets.
Dan Cole wrote about CO2 generation several months ago in this column, and so I won't go into extreme construction detail. Please refer to his article which can be found at www.mops.on.ca. To build the generator, you'll need the following items: 2 litre plastic pop bottle, some air line tubing, sugar, baker's yeast, baking soda, and some silicone or hot glue. Drill a 1/4" hole in the centre of the bottle cap. Insert the air line tubing so that it sticks through the inside of the cap by about one inch. Then using either hot glue or silicone, thoroughly seal the tubing to the cap.
The CO2 is produced by half filling the pop bottle with warm water no hotter than 40-45C. Using a funnel, add 1/2 cup of sugar, and about 1 teaspoon of yeast - mix well. Some people add a teaspoon of baking soda to this solution to extend it's life, you may want to experiment with this.
There are numerous ways of injecting the CO2 into your tank. Simply letting it bubble out of an airstone will work, but this method isn't overly efficient since most of the CO2 bubbles escape to the surface. The ideal injection system would allow all of the CO2 to be absorbed by the tank's water without letting any of it escape to the surface. To achieve this we need to build a CO2 reactor. I've experimented with several reactor designs, and the system which seems to be the most efficient at dissolving the CO2 bubbles involves using the impeller of a pump to smash the large CO2 bubbles into a fine white mist of CO2 'bubbletts'. T
hat's all for now. Next month I'll describe in detail how to build this almost 100% efficient CO2 reactor, and how to plumb it into your tank for maximum efficiency. Until next time, say 'hi' to your fish for me...