My pond is a long triangle shape and due to the large size at one end and small size at the other I have 2 flaps of extra liner material right at the bottom of the pond. As I filled it with water I put rocks on it to hold them down and this worked great, but as soon as I removed the rocks the flaps basically became bouyant. They flap around in the water. Is this state something that will go away? I was expecting the weight of the water to hold it down tight, will that happen eventually? If not I think I can get it pinned down with 1 or 2 rocks per flap, but I don't have any other rocks in the pond so I was hoping to not have to do this. Any advice would be appreciated.