To lower Hardness we recommend using Cal Treat if you have a D.E. Filter to remove hardness approx. 200-400ppm
. Add 2.5 lbs (one bottle) of Cal Treat per 15,000 gallons.
Otherwise, if your source water is 300ppm less hard than your pool water, you can partially drain your pool (up to about 1/3 of the way down) and refill.
If your source water is also hard, consider balancing using the Hamilton Index to compensate for your hard water.