For my most recent batch of makgeolli, I decided to experiment by increasing the duration of fermentation from 7-10 days a doubling of 16. The chongu layer turned a deep amber, and the rice solids had visibly dissolved to near liquid.
I proofed the yeast and nuruk, added a bit more yeast, and also 2 Tbsp. of sugar to the mix at the beginning. Much bubbling stopped around day 9, but started up when the jar was slightly shaken when I moved it to check on the brew.
I also added 3 cups of water for dilution, instead of 4. I will refrigerate the brew and then taste it to see if more water needs to be added. I halve the original recipe, using 2 1/2 cups of rice. Adding only 3 cups of water, the final product yielded about 60 oz., just under 9 cups, at present dilution of 3 cups of H20.
Taste test later!
...can't get enough Korean Food!!! :-))