Hey guys...I haven't posted in a long time but I need some help for my brother...
I'll start with an interesting story. My brother recently set up an outdoor pond and put his turtle out there but it escaped. He went to show me and I said I didn't see his turtle and that's when we realized it..we couldn't find it. Today his neighbor (who he asked the previous day if he had seen the turtle) just happened to see her head sticking out of the mulch in his huge front yard garden and now she is back indoors after being lost for 1-2 days for the time being.
Now I need your help. We may have very easily overlooked something, but we've never done this before so it's a learning experience.
His 100 gallon preformed pond is simply the plastic pond in a dirt hole. We backfilled it as much as possible and then filled it up with water, but it always manages to get pushed up or down and sags for some reason..probably because water is seeping down the side or something. What do we need to do to stop this? It is extremely noticeable and the pond is virtually unusable at this point. I'm thinking we should backfill the sides with sand but I need suggestions. Thanks.

