i did not put any sand under my mats. my dirt was not perfectly level but you could never tell with the mats. now, my pavers were perfectly level. once the pool was up, i went around and trimmed the mats so they would not stick out from the pool. then i put the gorilla pad on top of the mats. this pic was from last year. i had the foam boards the first year, i really did not like them. i really like the softness of the mats.
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