I have fairly modest 1,000 gl pond with bottom drain. Because I started a couple of years ago with some really small fish I replaced the normal dome cover of the (single) bottom drain with a very course plastic sieve cover (to stop them being drawn through). This has worked well until now and the fish are, of course, much bigger. This year a layer of a gelatinous substance (some type of algae I guess) that had gradually built up evenly on the whole inside surface of the pond is now coming off in pieces. Because it is soft, it is drawn to the bottom drain sieve and is lodged in place by the water flow. It soon blocks the drain and interrupts the whole flow of water and filtration process (Cloverleaf Filter) so I am having to clear it daily with my pond vac.
Does anyome know what this gelatinous covering is? More importantly how can I get rid of it and stop it forming again? I did have blanket weed problem last year, but the CloverLeaf treatment worked fine and there has been no recurrence this year.