Have you considered 'for every action there is a reaction' and what that might be?
Your visibility problem may not be so bad. It sounds like you want your pond to look more like mine, and I, yours. My pond, I can see bottom in six feet of water. The problem - seaweed is thriving in depths past ten feet deep and mats are forming on the surface. The plants keep the water clear, so much so that, an algae bloom cannot get going which would help to block light that would otherwise keep the seaweed problem at bay.
I'm working to reduce nutrient levels as well, but at the bottom layer, a couple treatments of beneficial bacteria pellets (Muck Away)so far this summer to help reverse decades of partially decaying organic matter. The goal for me, to slow down the seaweed and to get an algae bloom (like yours) to block the light from reaching the bottom to keep it that way.
