Using Plastic Under The Pool Sand

by Amy Miller
(Convoy, OH)

I'm so confused! We bought a used 24' pool. I bought a new liner and we have the area ready for the pool and are getting ready to order the sand.

Do we HAVE to put anything besides sand under the liner? I have some people saying yes and some people saying no. Thank you for such a great site!

Amy

Hi Amy

You don't have to use anything else besides sand. There a few reasons you may want to, but it is not necessary. The majority of my installations do not use plastic under the sand. I level the ground, put down plenty of granule weed killer and then the sand.

I feel that if your liner ever gets a hole in it the water will not get trapped between the liner and the plastic and mold or turn into algae. I have pulled old liners out of pools where the sand was completely coated with ugly green stuff. This does not happen when the water is allowed to soak into the ground.

I might consider using plastic if the pool is going to be installed near trees or other vegetation. If that is where the pool has to go, and I know it is only a matter of years till the roots are happily growing under the pool, I would try to protect the pool base with plastic. This could add several years of time before the roots are noticeable. When they do become a problem the liner needs to be taken out and the pool bottom cleaned out and re-done.

Plastic can also be used if the ground is very rocky. If the pool is going on a base of crushed granite I may want some extra protection between the sand and the granite. Granite is an excellent base for a pool but it can be rocky. Extra sand can be used but I would rather use the plastic and not have to use extra sand.

If I know the area where the pool is being installed has well established nut grass I will use plenty of weed killer and then several layers of heavy black plastic. Most of the time, this keeps the grass from growing through the pool liner. Nut grass can be such a pain.

Using plastic, or not using plastic, is OK, as long as the liner goes directly on top of the sand. I would not try to cover the sand with anything as that would leave too many footprints.