We left ours out until we saw how well it held water. After two years we decided to abandon the idea of a liner and accept the fluctuation. We are making the rock work to our advantage by reducing erosion, providing cover, looking interesting, etc. During a recent period of heavy rains and inflow we siphoned it down and added more rock, plants, and SMB nests. Whenever it used to rain heavy we would get mud into the pond. With the rock and plant material we have added this has been greatly reduced. We have only lined the first three to four feet with rock and left the rest bare.
