Hey RM,
I think a lot of it is organic between the leaves and all the weeds I have. 12 inches in a year? Wow! I won't have aeration out there for another year I guess. I didn't know the tilapia ate stuff off the bottom as well? I know they make a chemical I can add that has bacteria in it but I am not sure how well it works? If I could get a few inches a year I would be happy!