Styrofoam Base with Sand Cove

by Dan
(Lake City, FL)

I'm considering using the 1" white Styrofoam sheets as the pool base. My plan is to line the corner with plastic and then build a sand cove.

Are there any potential problems with this that you can see?

I read this about foam on another site:

"After installing your swimming pool liner and filling the pool with water, the pool liner gets sucked into the groves and indentations of the foam. You will begin to notice growth of algae, mold , and even fungus. That nasty, disgusting algae, mold, and fungus is embedded under the pool liner between the foam and the pool liner in all areas that the foam was installed. The only safe way to clear pools of algae and fungus is removing the hazardous foam and installing replacement pool liners."

I value your opinion. What are your thoughts on this?

Hi Dan.

For the first question I would not combine sand and foam. There is no way to keep the two separate and once the sand is on or in the foam it will stay there and could later cause problems with the liner. I would use the preformed cove with the sticky tape on the back for around the edges. Once the foam is down I fill in all the gaps around the edges with the left over foam, packing it in good, and then tape the foam cove to the wall over the foam base. Cleaning the foam before installing the liner is critical, any dirt, stones, pebbles or even pieces of foam show up later when water is added to the liner.

As for the algae under the liner, it could happen. In my experience, changing out thousands of liners, it's a rare occurrence, but I have seen it. Not with a foam base but with sand where plastic was installed under it. My belief has always been that sand should go directly on the dirt, no plastic, that way if the liner ever leaks the water has someplace to drain, otherwise it is stuck under the liner and can cause algae growth.

The places where I saw the worst growth were under liners that had been leaking. So if your liner never leaks you will probably be just fine. If it ever does leak fix it or replace it. The other thing is the time frame, you are looking at many years before any growth would become noticeable under your liner, if it ever does. This is usually only discovered when changing a liner, at which time you remove the algae, clean it up and start over. I see this as only a consideration but not a major problem.