Even with proper pool care and maintenance, we recommend draining your pool either at the beginning of the pool season or at the end of the pool season. There are several reasons why pools should be drained periodically. Eventually, a point is reached where the water cannot be maintained properly regardless of how many chemicals are used.
Total Dissolved Solids
One important reason you should drain your pool at the beginning or end of every season is due to TDS levels. TDS stands for total dissolved solids. These dissolved solids in the pool water consist of metals, minerals, salts, and more. Virtually everything that enters the pool water contributes to the TDS level. More specifically, these things can include chemicals, sunscreen, hair products, sweat, etc. The only way to lower the TDS level is to dilute the pool water with fresh water. If a pool is being used consistently without being drained, you can imagine how the TDS level might continue to rise over time and begin to cause issues with the pool chemistry. By draining at the beginning or end of the pool season, you can start a new pool season with a low TDS reading and not have to drain mid-season due to high TDS levels!
Stabilizer
Another reason to drain pool water at the beginning or end of every season is due to stabilizer readings. Pool stabilizer, or cyanuric acid, helps to stabilize the chlorine in the pool water. We call it "sunscreen for your chlorine" because, without stabilizer, chlorine would be burned off quickly by the UV rays. Stabilizer increases the life of this chlorine and helps it last longer. Having stabilizer in pool water is a good thing, but when there is too much in the water, it can cause your chemicals to work less effectively. Because of this, you would end up spending more money over time. The most effective way to lower high stabilizer levels is to drain and add fresh water. By doing this at the beginning or end of the season, you could start with a good stabilizer reading and worry less about your chemicals working effectively.
How to Drain Your Pool
Before draining your pool, the groundwater levels should be taken into consideration. If these water levels are too high, they can actually cause your pool to pop out of the ground, and no one wants that. Each type of pool is built differently and therefore has different directions on how to be drained.
Vinyl Liner
Because the water inside of a vinyl liner pool helps to keep the liner in place, you should on every drain to the top of the bottom step in a vinyl liner pool. Going past the top of the bottom step can cause the liner to float. You can drain by placing a cover pump inside of the pool water and pumping the water out with a hose.
Fiberglass
Similar to vinyl liners, the water inside of a fiberglass pool also helps hold the pool in place. Draining below half of the water can cause the pool to pop out of the ground. You can drain half the water out of a fiberglass pool and refill. You can also do this with a cover pump.
Concrete/Gunite
Concrete and gunite pools are also susceptible to popping out of the ground if too much water is drained out of them. For this reason, they also should not be drained below halfway to reduce the risk of coming out of the ground. This can also be done with a cover pump.