When to change co2 bottle

[widow-maker]

Could someone please tell me when i should change my co2 bottle had the system almost a year never changed it before noticed the psi going down now. I have a fe to replace the bottle with should the bubble counter be changed or will the bubbles per second remain the same once the new bottle is fitted. Find attached pic of the dials on the reg.

Thanks

 

[John q]

Should be good for a while yet if its taken 12 months to start dropping. Mine last about 6 weeks and i usually get about a week out of it once it starts dropping.

If you're generally on hand during the gas on period then just let it run out and swap over to the new bottle.
Bubble rate should remain the same unless you knock the needle valve when changing over, so keep an eye on it after the swap just to be on the safe side.