Thanx so much, sounds like good advice and will give the bomb a go. The only standing water is in the run off trough, I cant really do much with it as it will just fill up again but will pump out what's in it and flush it away down the sewer, then put some of that gnat off stuff in it to try keep em at bay. What a plonker though, never thought to check the run off, it's plumbed in and just drains itself but the drain is half way up the side so it is always half full, I figured that heavy stuff would sink and not block it up that way, Duh! Thanks again.