My pond was was over 60 years old and very similar....about 2-3 feet of muck in the bottom. I pumped out some of the muck into large dewatering bags, that when dried out serve as my elevated garden. I had the best tomatoes and vegitables I ever saw last year. My goal was to remove the muck (black and thick and anaerobic and hopefully remove some potential nutrient load fueling algae problems. However, I have more algae now than before. I will hit it with cutrine plus today and then put in blue dye to minimize light penetration along with barley straw bales. I will probably do more mucking after spawning season....I love the soil that results.
