This is the second time I'm doing a no-boil, fast lacto sour. I had nearly 3 lbs of grain (with about 9% acid malt) for a 1 gallon batch. I did BIAB for 1 hour and put right into a fermenter. I let it cool down to about 100 °F and pitched 2 pills of Lactobacillus plantarum from Swanson Probiotics. It sits in a room without A/C, so the heat remains fairly high especially now with a heat wave in Southern California. Day 2 I added 2 more lacto pills.
Here is a pic from day 3, which looks fairly normal:
On day 4, I noticed a patch of cotton-looking growth at the top left of this picture (hard to notice):
pH dropped from 4.54 on day 1 to 3.57 on day 4. I tasted a little sample from day 4 and I can taste the sourness. The smell seems normal: there is no vomit, fecal smell, but rather earthiness.
Should I remove that cotton growth? Keep it and boil? Just let it go normally? Last year I did this same method (BIAB, no boil, lacto, saison yeast, dry hop) but with L. delbrueckii and had a great success. But with this cotton thing, I'm slightly concerned.