Overcarbing problem

[pursuit0fhoppiness]

Hey all, I've been homebrewing and bottle conditioning for a year and a half now. I've made some sours with Brett and Lacto, but keep all equipment separate from my clean beers (except bottles). I've also used 3711 with my clean equipment before I knew what diastatic yeast was.

Lately, some of my batches have begun to gush after they've been in the bottle for a while, and some have even started to gush within just a few weeks. I re-use my bottles, rinsing them after drinking and then giving them a StarSan clean just before bottling the next batch.

My question is, could there be some diastatic yeast or Brett still in the bottles after the StarSan rinse, fermenting both the priming sugar plus residual sugars left after FG was reached, causing my beers to overcarbonate? Note, the overcarbed beers haven't shown any "infected" flavours or aromas. They just foam over upon opening the bottle. Should I be using more than just StarSan since my bottles have been subjected to 3711 and Brett?

 

[RPh_Guy]

My question is, could there be some diastatic yeast or Brett still in the bottles after the StarSan rinse, fermenting both the priming sugar plus residual sugars left after FG was reached, causing my beers to overcarbonate?

Yes, possibly in the bottles or yeast may be contaminating the beer in the fermenter or any equipment in the bottling or handling process.
I'd definitely suggest breaking everything apart and soaking in warm PBW or similar cleaner, to remove any biofilm that may have formed.
Metal, silicone, glass (depending on quality), and rubber can be heat pasteurized.
Consider getting new plastic parts if the problem persists since biofilm loves plastic and it's more prone to scratches that can't be thoroughly sanitized.

StarSan is fine, that's not a problem.
Caveat: Only clean surfaces can be sanitized, so a cleaning soak is a good idea.

There are also other possibilities for overcarbonation ... Malt quality, under attenuation before bottling, poor mixing of priming sugar, or over priming.

Hope this helps

 

[pdxal]

Posting more information might help us help you.
For example:
Are you sure these beers were done fermenting? How did you know?
What has been the gravity at bottling, then the gravity after letting a gusher go flat and measuring it. If they are the same, no further fermentation of beer/wort occurred, aside from the priming sugar, has happened and you added too much priming sugar.
How long have the gushers been refrigerated before opening? Were they agitated some before opening, like transporting them to a friend's house?

 

[isomerization]

The fact that every bottle is gushing suggest it is upstream in your process. For example, something could be in your bottom bucket spigot or bottling wand (if you use those).

+1 on is fermentation really complete?

 

[Vale71]

For the record it's actually diastaticus.
If you used it with your regular equipment then there is a possibilty you might have a primary infection (i.e. one occurring prior to packaging) or if you reuse bottles and have a small stock it's also possible they have all been contaminated with diastaticus.
A simple rinse and StarSan might not be enough. StarSan is basically an acid wash and yeast is rather resistant to acid washing, I would suggest using an oxydizing agent such as Iodine or peracetic and/or heat treament of equipment and bottles.