Chemical CO2 additives?

sign up to the forum of UKAP's (uk aquatic plant society)-its a great friendly forum, with an amazing amount of very knowledgeable people. ask this question on there in the el natural section, people will be very intrested as to what you have to say about the walstead method (including me) i find it very intriguing. start a journal if you want to show of your scape, there are people on there that go from absolute newbies to world wide experts and renownd aquascapers.