I'm looking on upgrading everything in my tank, first was the filter, then the lights, now I'm looking for some Co2, I'm wondering what to buy though. I've seen D-D 600gm disposable tank kit, £124 looks similar to JBL brand but minus the gauge, I believe it only has the working pressure gauge and not the other.. the other is bottle capacity right? I'm also looking at JBL brand u401 £120 and m601 £168. Whats the difference here? I read the 601 can fit larger co2 canisters, can the 401 do this? EDIT: after more browsing I understand JBL does not come complete with solenoid, and for that cost, definitely no. Or, which I'm leaning towards. Buying a fire extinguisher and a regulator and solenoid and making my own? I just don't know. Do the majority of regulators fit the threads on extinguishers? Regulator+Solenoid ~ £60 and 2kg extinguisher £37 What should I do?