Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
STS works very fast to remove KH.
Tap: about 4 degrees KH.
Tank (88 gallon tank) with STS (40 lbs, new) hits zero in just a couple of days.
When I add baking soda to restore the KH to about 3-4 degrees it again hits zero in just a few days.