disappearing fizz

[squirrell]

I bottled 4 coopers batches in October/November using pet bottles and carb drops. The first lager batch took ages to carbonate but now is plenty fizzy with a great head. The pale ale, real ale, and Irish amber ale recipes all carbonated nicely in the first month and were great drinking up till Christmas. But for some reason over the last 2 to 3 weeks they have lost most carb and no head after 30 seconds. I don't think its the glass as the lager is fine, so could it be:

- the pet bottle tops are not screwed on tight enough?
- the bottles were filled up too high or not enough?
- the ambient temperature where bottles are stored has dropped since Christmas?
- pet bottles always lose fizz after 6 weeks?
- I am not leaving them in the fridge long enough pre drinking?


Its pissing me off because they are all nice tasting, except the lager which has the best fizz and head.

 

[Mr. No-Tip]

I don't have a definitive answer for you, but in my experience PETs can still hold fizz close to a year on. (some would argue they might start oxidising by then but that's another debate).

Are you re-using the lids? I've never done that myself. I was surprised to find a lot of people do. That could be a cause, particularly if they were loose.

Out of probably around 50 PETs, I've only had to turf one for losing/not gaining carbonation that I thought was the bottle's fault.

 

[damoninja]

As long as you're using good NEW lids and bottles you shouldn't have any issues. I've heard people say they've kept them for 12 months.
Tightness may be a thing...

If you reused lids or didn't tighten, you can always pop the lids off, plop in another carb drop and seal up with some new sterilised lids