Add acid
The only way to lower your cya level in your swimming pool is to partially drain your pool and fill with fresh water that will lower it or if you want to lower it to almost nothing completely drain your pool and start over but keep in mind chlorine tablets will raise your CYA level More information in the related link below.
Add potash. See your pool shop with a sample of your water and the size of your pool and he will give you what your pool requires.
The only way to remove Hardness is to partially drain and refill your pool.
use something called soda ash you can find it at a pool or spa store
No
Remove some or all of the water
Raab's Pool Supply can help you find pool supplies for all of your summer pool needs. They have a variety of pool products are located in Big Rapids, Michigan.
If the calcium is a result of pool chemicals, draining some or all of the pool water will lower the calcium hardness level. If the cause is the fill water, commercial hardness reducers or chelating agents will bond with the calcium to keep it trapped in solution.
The only way to lower it is by removing some or all of the water.
Muriatic Acid....Be real careful though.
baking soda