As the days wore on it became crystal clear to Lily and Kat exactly why those bubbles needed to be popped and clean. After being at the pond for two days they were nearly constantly working to clean off new bubbles as they formed. Kat even had to work through the last night without sleep because resting the night previous had the pair wake to find their cultivators' legs covered in gunk from the few bubbles that did pop, with the rest of their legs covered in bubbles.
It was constant work at this point. Kat also had to waste time digging a larger hole for the poisonous runoff. What seemed to be perhaps the worst part of the poison was that it kept expanding, constantly making more if itself more like a virus then a poison. At this point Xiang's and Yang's legs were more holes then leg. Only their cultivator physique prevented them from collapsing completely.