I use H2Ocean for the last few years and the buckets have always tested around 1200 ppm. I wouldn't change salt because of this. I just buy the 4kg tub of Fauna Marin Magnesium chloride and add 180 mL to eacg 15-gallon bin of saltwater I mix up. This boosts it to about 1400 ppn which is enough to keep my tank at 1350-1375 ppm without dosing. Works for me.
Sent from my Dungeon using mad Ninja Skillz.