Yep their change in water made a rather large difference, the alkalinity more than doubled:
pH 7.6
Total Dissolved Solids (TDS) Est 502
Electrical Conductivity, mmho/cm 0.84
Cations / Anions, me/L 8.2 / 7.8
ppm
Sodium, Na 78
Potassium, K 6
Calcium, Ca 69
Magnesium, Mg 14
Total Hardness, CaCO3...