Hi ive been running co2 for about a month and a half and i think the bottle has run out.How can i tell when the bottle is about to run out, there are two meter things one 1-160 one 1-4 so do those help with telling when its going to run out?Also ive just got a solenoid valve is it ok to have a bit of tubing between?I tried to make it as short as poss i dont know whether pressure will build up too much or soemthing? thanks