My CO2 ran out so I went and got a refil and was given a replacement bottle. I've now come home and placed the reg on the new bottle, connected it all up but I cannot obtain a steady flow of bubbles. I set them at 1 bps but 2 mins later its either stopped or it closer to 5 bps. When it stops I slowly turn the needle valve, nothing, nothing, 5bps again. No inbetween. I've removed the reg from the bottle and put it back on again but same thing. I can't see how changing the bottle could effect this and sounds like a faulty regulator BUT it worked fine when it was on the last bottle. I am using an Aqua Medic Regulator Any ideas what this could be?