One of the most important things any owner of a vinyl liner pool needs to know is you should NEVER drain the water from your vinyl liner swimming pool.
The water in the pool helps hold the liner into place.
If you drain your pool you can cause your vinyl pool liner to shrink and upon refilling, if the liner has lost its elasticity it can cause the liner to rip or tear.
The liner can also become hard and brittle. The older the vinyl material is the more likely this is to happen.
If you have to patch a hole or puncture, you will not need to drain your pool as most vinyl repair kits are designed to work underwater!
Also if you drain too much water out of an above ground pool, it can lead to the pool wall collapsing.
You can help protect the life of your liner by not draining your pool. It doesn't matter if you just want to drain your pool for a short window of time, the bottom line is the only time you should ever completely drain your vinyl lined pool is if you're wanting to replace your vinyl liner.
A vinyl inground pool should also not be drained for cleaning, as again it will likely damage the liner. If you're concerned about issues like green water, don't drain your pool! Check out this article on pool algae cleaning instead!