I have 8 DIY 2L CO2 bottles. 3 are on my 29g tank.

I just changed one to a new bottle, shut off the valve, installed the new bottle and left it for 2 hours (that is usual). I then went to turn it on. Just before I did, I noticed one of the other bottles was collapsed in on itself. Since it should be generating gas it should be expanding if the tube was blocked, or if not blocked just pumping CO2 bubbles into the tank.

So, I opened the valve on the new bottle -- it took about 20 seconds to settle down as it had built up a bit of pressure. Then I opened the top of the collapsed bottle and let it expand. I then put the cap back on and suddenly bubbles were appearing like mad into the tank as this bottle collapsed again. I di this 3 times, each time the bottle collapses as bubbles go racing into the tank. I don't know bubbles of what for sure, nor do I know where they are coming from or how the bottle is collapsing. Take the cap off and bottle expands back to normal. Its like something is sucking the gas out and pushing it into the tank.

Either I have the greatest invention of the year, or my bottle is possessed.

Anyone have any other ideas?

At rest (me not fiddling with that bottle) there are fine CO2 bubbles coming out of my diffuser as expected. The other two bottles are just fine.

Oh darn thought I had something that would make me millions, a rogue pop bottle. Figured I would have people lining up at my door to come and view the bottle

Here is what happened. The tube from the 3 bottles goes into the input stream of a 600gph powerhead. The actual input to the powerhead got blocked with dead leaves, totally blocked, so the powerhead was sucking from the bottles. Seems that only the one bottle had in fact been flattened before being put into use so it was weaker than the others.

Oh well, maybe I will make my millions next time

Many have done that and sucked all the brew into their tanks.

Regards,
Tom Barr

I had heard about sucking the brew into tanks -- couldn't believe it could happen -- we all have things to learn

The more solution you put in the bottles the less likely they are to colapse because the weight of the fluid holds them in place. However the more solution you put in the bottle the more likely it is to get sucked into the tank when the bottle does colapse. A definate catch 22. The sad part is that a check valve can't prevent this because it sees pressure on one side or vacuum on the other as the same thing a difference in pressure going in the same direction. The best solution to this problem I have found is to use more rigid bottles, like the thicker plastic bottles that Gatorade comes in. It takes a lot more of a pressure difference to colapse a Gatorade bottle than it does to colapse a 2 liter soda bottle. Definately replace the bottle that colapsed on you, because once the bottle has been colapsed or kinked it will colapse under a lower pressure difference than a newer unkinked bottle.

Good thought -- never thought of that. This one had collapsed when I had rised it in hot water then forgot to re-rinse in cold before capping it.
Its headed for the garbage -- no headed for my dog, he just loves to chew those plastic bottles. Hope he never decides that the running CO2 bottles would be good -- I think even if he got into one, the alcohol smell would put him off, he does not like any kind of alcohol -- so far.

I wouldn't trust the dog, I once had one that would knock over any unguarded beers just so he could lick up the mess.

OK -- can the dog -- oh oh -- he read this over my shoulder, now I'm in trouble, he weights 120lb