That unit uses mathematical calculation, as opposed to actual measurements, to determine your co2 needs. Accordingly, it's not going to be all that accurate.

Check out this unit. It's about $90 less and it measures the co2 in your air, but doesn't have the valves. If you could pick up a set of valves for 50-100 quid you'd be a lot better off, controler wise, without spending too much more. You might be able to find this in the UK with the right cord ends and voltage.

PC :thumbsup: