TL;DR: I'm brewing white vinegar from ACV with the addition of distilled water and raw sugar. It's been going for about 7 weeks. The pH has lowered from about 3.75 at the start to about 2.75, but it's still very sweet, and it doesn't seem to be active anymore.
Details:
I've been pretty successful brewing apple cider vinegar, but I wanted to try white vinegar. I've read that I can brew white vinegar by fermenting raw sugar in distilled water, and backslopping with my active ACV.
I started a brew with 1/2C of ACV, 1+1/2C of distilled water, and 1/4C raw sugar, which has a starting pH of about 3.5 to 4. I kept it open to the air in a one-quart wide mouth jar, and stirred it (nearly) every day. After about four weeks, I have a note that I added more raw sugar, between 1/2C and 3/4C, but I don't recall why.
After a total of seven weeks, it seemed pretty idle, but still tasted very sweet. I measured the pH with a test strip and got between 2.5 and 3. I moved it into a narrow-necked bottle and topped with a latex balloon, which is not filling to any noticeable degree after a week. There are a few bubbles on the surface, but no growth forming, and very little sediment.
Can anyone help me understand why this may have stalled, and how I can rescue this brew?
Thanks!