I’ve an 8’ x 8’ pond with graduating depths, from 2’ - 3+’. I’ve goldfish, that are 4 yrs old and very large. It seems a few of my potted plants have grown into the muck and formed a tiny land mass. Calla lilies, canna lillies and a corkscrew Willow. I like it but I notice water level goes down a couple of inches every few days in warm weather. I’m wondering if it’s plants needing water, or roots causing leakage. It’s a very heavy gauge liner. Needless to say pond muck has built up quite a lot. I’m 79 and very limited as to what I myself physically can do. Any recommendations especially about the muck.