Tap-A-Draft Canister question... CO2

[wookiemofo]

how will I know when to replace the CO2 carts? I have my first stout in there, so I have a CO2 and a Nitro cartridge. So the beer is already sort of flat... just wondering how I'll know. Does it just stop pouring? And is it safe to just replace them at any time?

Thanks for your help

 

[Shooter]

It will start pouring REALLY slow. I wouldn't just replace them if there not close to empty. They're going to release any extra CO2.