TMC have brought out some really great CO2 sets that are just perfect for smaller aquariums up to 100L or so. For about 15 months TMC have successfully been introducing planted aquarium goods which is a great move for them and a true reflection of where the planted aquarium market is in 2010.
The TMC AquaGro CO2 sets (Hobby & Expert) are small and are a great introduction into pressurised CO2. Both types of sets are easy to set up and the main difference between Hobby and Expert is that Hobby uses plastic bubble counter, diffuser and non return valve - in Expert the equipment is glass.
At Aqua Essentials we lean towards planted aquarium goods as that is what we specialise in but we also have a passion for marine products. If you're looking for other CO2, click here.