During the construction of a pool, the hole that is dug is slightly larger than the pool, and the dirt that is backfilled is not as compacted as the undisturbed soil around it. This can create a "bowl" which holds water for a while before that water is absorbed into the surrounding soil. When the level of this groundwater outside the vinyl lined swimming pool comes up to or is higher than the water in the swim pool, the vinyl liner is in a "floating" situation. As the water on the outside of the swim pool liner is absorbed into the soil, the liner is again pressed against the pool support structure, but not always like it was originally. The result? Wrinkles. How can they be removed?
Groundwater often comes from the the landscaping, surrounding the swimming pool, directing rain/snow runoff water under the pool deck and into the area around the pool. It is important that this be corrected by directing all runoff water away from the pool area. Check where your gutter downspouts direct the water.
If you have just removed the cover to your pool, and have not filled the pool with water yet, and you have found that the liner is "floating", now is a good time to prevent wrinkles from forming. As you are adding water to the pool you will be able to move the liner around to position it as it should be as it begins to sit back against the walls and floor. You can do this using a pole with the pool brush on the end or by padding the end of the pole with a rag. Do not push so hard that you poke a hole in your liner. You will need to "baby-sit" the filling process until the liner is firmly seated.
What if your pool is full and there are wrinkles in the liner? If there are only a few small wrinkles, you may be able to remove these by using a toilet plunger. By plunging around the wrinkle you can spread out the liner in that area thereby removing the wrinkle. Do not plunge directly on the wrinkle but rather just above, below, or to the side.
If the pool is full and there are too many wrinkles to plunge out or the wrinkles are so large as to be folded over we would strongly recommend calling in your local pool service professional. When the liner has folded over, it will most likely require draining the pool and resetting the liner to correct. Anytime you drain a pool, there is the possibility of structural damage taking place. This is not the time to scrimp. You could lose the whole pool.