Even without water, concrete may start to sink. So while in theory it's possible to leave the pool empty for months, at The Complete Backyard we only recommend leaving it empty for up to 2 weeks. Once you've drained the concrete pool, consider refilling it as soon as possible. It may be surprising to know that you shouldn't leave your pool empty.
Most guidelines for closing a pool recommend simply reducing the water level below the level of the skimmer and the jet. This is done to ensure that the pipes remain clear and are not at risk of breaking or freezing. If you're wondering why it's not recommended to leave some water in the pool while it's not in use (after all, this water will have to be discarded when you're ready to use it again), there are a few reasons. Owning a pool is an important investment and you need to make sure you take proper care of it so that it lasts for many years. Leaving some water in the pool will help protect it against freezing and dirt, but it's also important to use the right chemicals to keep the pool safe.
An inground pool will need to draw in more water, and you'll also want to make sure you have a tight-fitting cover that doesn't collect water. The chemicals you add to the pool are designed to clean the water and, as a result, the chemicals will contact the walls and floor of the pool for some cleaning power, but they don't “scrub” these surfaces naturally. They can also include the walls of the pool, a ladder, a pump, etc., to build an aboveground pool. Problems that cause a pool to drain usually take a day or two to fix, which is too long and can be detrimental to an above ground pool. You may have to remove water from the cover due to melting snow or rain, so be sure to unplug any electrical equipment you use in your pool.
You may want to consult with a pool expert before undertaking this work on your own, as they may be able to repair the pool with the water still in it. You may want to add some accessories compatible with this item, such as the heavy-duty hose for Poolmaster 33430 vacuums to connect the vacuum to the Hayward Vac pool skimmer for total and simultaneous cleaning. Perhaps it's time to change the pool liner due to a puncture or leak, or you haven't closed it properly during the winter or maintained chemical balance, and the water isn't hygienic or you're throwing the pool in the trash. But if you really want to make repairs before winter comes, make sure to refill the pool immediately after the repairs are complete, prepare it for winter, and close the pool for the season.
This can damage your pool by breaking these materials, making it unstable and prone to cracking or disintegrate.