I just tested a new bucket that I bought about 1 month ago at J&L, luckily haven't used it yet. I screwed up a little on the salt mix so these levels should adjust to even lower at 35ppt. I tested salinity with a refractometer and Alk with a salifert test kit:
Old bucket of kent @ 38ppt:
10.9 dkh
New bucket of kent @ 39ppt:
3.6 dkh
Going to email J&L tommorow and buy a new bucket of Seachem.