I am setting up a 20g tall tank with pretty simple plants. But I want to do it low-tech due to my $142 budget. The plants I would like to use so far are Java Moss (or other moss), Java Ferns, Dwarf Hairgrass, and possibly some rotalla sp. not sure what plants I want for the background but it seems the best ones need some CO2. So my question is should I setup a DIY CO2? If so, how would I go about making one?