New bucket 'o salt - dKH high?

[Shy_Koi]

First time I've ever checked the dKH of a brand new bucket of salt, so I don't know what it generally is. The fresh saltwater seemed a bit slimey on top, hence the test. (Container was clean w/ newly made RO/DI water) Been aerating about 18 hrs.
It's 13 dKH (Salifert), which I know is not *that* high, but I run my tank at 10.
Will doing a 10% waterchange w/ this new saltwater be harmful?
~Tamara