It's not just how much brine is pumped into the ponds. There are...

It's not just how much brine is pumped into the ponds. There are actually a series of ponds - say low concentration, higher concentration, and harvest. Initial concentration occurs in the low concentration, then some of that is pumped into the next ponds for further concentration, then finally into the harvest ponds for final concentration. The aim is to have sufficient high-concentration brine in the harvest ponds to keep the plant operation at maximum capacity.

So the cascading of brine between the levels of pond needs to be carefully controlled. The issue they had in the September 2017 quarter was reported to be the result of errors in the algorithms used to determine when and how much brine is moved between the stages of ponds. This issue was supposedly fixed at the time, but one wonders whether there are still issues given the poor results in this last quarterly (or perhaps it was just unseasonable unfavourable weather. We may never know.)