Hello fellow Aussie!
If you have just started out, pressurised CO2 is probably not a great idea. This is because it takes plenty of research and experience to master. I know of the Fluval system you are referring to, and I agree that it's probably more hassle than it's worth. This is because it is high maintenance and expensive in the long run. I've seen a few people buy them and sell them within a few months, because they got sick of changing the canisters all the time. Using paintball canisters helps with the overall cost, but this still leaves you with a system that is high-maintenance.
While you are starting out it might be best to use Glutareldehyde as an alternative source of carbon for your plants. It's not as effective as pressurised CO2, but is more manageable for the beginner. The most popular brand on the market is
Seachem Excel. Excel can accellerate plant growth by 2-4 times if used correctly, and in conjunction with adequate light, temperature and fertilisation. Pressurised CO2 can boost plant growth 10-20 times which is great, but it means that your plants will consume nutrients very fast, and things can very quickly fall out of balance. This equals an algae nightmare. To use pressurised CO2, you will need a near perfect balance between light, temperature and nutrients, as well as adequate water flow and so on. It takes time, effort, research and experience to achieve this balance. Problems happen very fast when things are out of whack with pressurised CO2, whereas Excel will give you some breathing space to deal with problems as they arise.
Dwarf hairgrass is a difficult plant to grow for the beginner, and I'm sorry to say that it may not survive.. I haven't seen great results with hairgrass unless combined with pressurised CO2. Check out this
list of low light plants for some more suitable options.
Check out this thread on using
ADA soils effectively. This will give some tips on using the substrate you've chosen.