Your incoming fill water may be hard.
Hardness increaser from your pool supply company
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.
Oh, dude, raising the total hardness in a pool is like adding calcium hardness increaser. You know, it's like giving your pool a little boost of calcium to make it feel all fancy and stuff. Just follow the instructions on the product, and your pool will be harder than a rock in no time.
No, baking soda does not increase calcium hardness in a pool. It is used to raise alkalinity and help stabilize pH levels in pool water. To increase calcium hardness, you would need to use calcium chloride.
The only way to remove Hardness is to partially drain and refill your pool.
Calcium chloride increases the hardness of water. Proper hardness is critical to balancing the water in a pool. Proper hardness is especially important in a plaster pool to prevent leaching of the plaster finish, which results in a rough surface. Calcium chloride can be purchased at home improvement stores at significant savings over pool supply outlets.
Probably the least expensive is to replace some or all of the water(dependind on hardness) with fresh.
Low Calcium Hardness in pool water means that there is low calcium in the water and is considered "soft" and soft water tends to be corrosive. It will etch away and your plaster and any metal object the pool water touches.
No, because it's not the chloride part that's responsible for the hardness, it's the calcium. Sodium chloride is actually used in water softeners, so it's not a great choice if you're looking to increase the hardness. You could use calcium hydroxide, though this will also make the pool more alkaline which may not be ideal.
Baking soda will not soften (remove calcium hardness) from pool water. It will raise total alkalinity.
Buffer and added hardness do the same thing in a salt water pool as in a fresh water pool. The buffer (sodium bicarbonate aka bicarbonate of soda) stabilizes the pH of your pool so that addition of acid or base doesn't change the pH very much. The hardness, mostly Calcium, helps achieve water balance to make the pool neither deposit (precipitate) excess Calcium Carbonate to your pool surfaces nor corrode (remove) Calcium from your plaster pool surface. The combination of pH, Total Alkalinity (adjusted for Cyanuric Acid), Calcium Hardness, temperature and Total Dissolved Solids determines whether your water is balanced. Just keep these values near their recommended amounts for your pool and you should be fine. If you're a techie and want the full formulas, do a Google search for "Langelier Saturation Index".
The best way to lower calcium hardness in the pool water is to drain the water and refill with water of lower calcium hardness. Have the calcium hardness tested for both the pool water and fill water. Ideal range is 175-300ppm. There are 'calcium reducer' products available through pool stores, but not sure how effective or economical they are.