You may need to drain your pool once in a while to get rid of Total Dissolved Solids, or TDS. However, there are several things you have to consider if you do this on your own.
The most basic concept to understand is that of “hydrostatic pressure”. It is not only your pool that holds water, but the ground on where it sits as well. When the pool is full, the pool water and the groundwater exert pressure against each other, maintaining an equilibrium that keeps your pool liners safely in place.
If there’s more pool water than groundwater, there will be no problem as the internal pressure will keep the pool wall from collapsing. As the water level decreases when you drain the pool, however, the pressure from the groundwater increases and pushes against your pool lining. This could cause creases and wrinkles, or even greater damage, on your pool walls.
A hydrostatic valve often installed at the deepest part of the pool serves to neutralize the pressure from the pool water and the groundwater, allowing the latter to seep in when its pressure is more than that of the pool water’s. When you drain your pool, however, the equilibrium could be totally disrupted and cause damages.
To avoid this, it is best to call on the pros to drain, clean, and refill your pool. They would know what to do to keep groundwater from wreaking havoc on your pool.