Yeah, that's what she said! Thanks.gianolrac;3881415; said:
Thought i'd stop being lazy and have a proper look at the leak. Cut the old silicone off the outside and could feel a gap between the the glass and the frame and no white silicone's visible on the outside side of the glass. Put a load of the black pond sealant over the space. Now leaving it to set, and yes it is good for setting underwater and i damp environments. Will probably rub some more over the top just before i start topping it (It's non-toxic to fish)