I have encountered a strange thing and I am writing about it because another member of my local brew club did also.
I use either Straight A or Oxy Clean (original version or a knock off) I filled my carboy with cold water, outdoor faucet, put in a measured amount using the spoon supplied. Let the carboy stand 3-4 days. Temperature here in Eastern NC dropped to the 30-40 at night. By the way I let it stand in my attached garage.
When I went to clean the carboy there was a crystalline deposit on the bottom and some on the sides. This has also occurred to my glass bottles I let stand in a plastic bucket, but not to the bucket or anything else plastic or metal. ONLY glass items have been affected.
You can not wash out or scrap off the crystals. I tried many methods and cleaners but nothing is removing these very fine crystals.
Any ideas what has occurred here? How to remove them. I do not thing they will have any effect on the beer, just have not tested it yet.
Frank ATF Home Brew Club New Bern NC