The coating usually referred to as a solid cover, is actually a large industrial PVC sheet. They are usually installed either with stainless steel fittings such as mesh caps or with aluminum bars.
They are very effective and are often sold as protective covers because access to the pool is very difficult. Unfortunately, the same access problem makes it difficult to move the lid when closing and opening a pool. This blanket is much more expensive than traditional mesh covers.
Some companies offer very thick lids that are made using rigid PVC with yarn. This lid floats on the surface of the water form a waterproof seal and bears the weight of an adult.
Although these cases are the most expensive choices, they are protective covers that can also be used in summer. You can buy different types of a pool at https://www.coversinplay.ca/.
Regardless of which cover you choose, it is important to measure the pool correctly. The manufacturer must know the right side of the pond to allow a good overlap.
This prevents dirt from coming out from the bottom. Most winter boxes have special protection when worn, which are sewn on the cover at certain points.
The manufacturer must know the dimensions of the pond in order to position it correctly. The grille must fit right into the pool. If it is too large, it will not fit between the walls of the pond and if it is too small it will not be well maintained at the edges.