This is new to me so bear with my dumb questions. I'm attempting to do a Berliner weiss by pre-souring the wort before the boil. I made a 4L sour starter of grain and dextrose to grow Lacto, kept hot (110-ish) for 24 hours. pH of starter was 2.9 when I pitched it into the wort.
So the first problem is that I collected a few too many liters of wort, which wouldn't be a big deal except I forgot about the 4L from the starters too. So my total volume was about 8L too much. My target pre-boil gravity was 1.028. Second problem was I forgot to take a gravity reading before I added the starter. So I'm not sure what my OG was. Even with 50% efficiency my wort should have been 1.020.
After 24 hours under a blanket with the carboys wrapped with brew belts, I took a sample. pH was 2.3 and the gravity was 1.016. The airlock was going nuts, so I think some yeast may have survived on the grain too and it was now fermenting.
So, now I'm not sure what to do about the gravity. I can either boil and ferment as-is, or I can try to fix it. I could mash more wort, I could use some DME I have on hand, or I could boil longer. I'm leaning toward one of the first two.
2.3 is lower than I was expecting. What pH should I target pre-ferment? I'm not sure what's typical for Berliner Weiss, but the lowest beer on Raj Apte's chart was 2.8.
Also, are there any concerns with pitching with such a low pH? Should I pitch more yeast than usual?