After losing 5-8" of water weekly since installation at the end of July, I've came to the conclusion that there's a leak at our main drain (with no help from the installation company who won't return my calls, grr). I've tightened the bolts on the drain plate. Is there anything else that can be done? I read on another site about a product called Fix A Leak but not sure if this will help our problem. Any help/advice would be greatly appreciated!