During the first few days of running the DIYCO2 when it begins bubbling be sure to keep daily checks of pH until you are sure it is running ok. If you need to adjust pH due to changes CO2 has made do so with non phosphate containing pH adjusters. If you are in doubt ask on the message boards here. Many pH adjusters contain phosphates. This will cause an algae bloom with CO2. Some examples of those with phosphates is a product by TLC for pH down and pH higher. Most pH adjusters do contain this so you will have to be careful.
Additionally you will probably need to add Iron supplements such as Flourish Iron and/or use a Flourite substrate. Also consider ordering a fertilizer such as Tropica's Master Grow. Tropica is world recognized for quality plants and plant products (which plants are only sold as a franchise Licensed name in the US since Tropica's plants are not eligible for import here directly) most of all ask people if you have questions.
Lighting is always crucial too. If you supply CO2 but only have a "dinky little low power light" you're not going to see any results.