Thanks for the input. Have finally got some aerators in and started using Aqua Shade dye. That made a difference already. Also placed some Biotix into the pond to help with necessary bacteria.

I placed some water lettuce and water hyacinths in a screened section and they are growing relatively well (of course it is the middle of summer). My pond never freezes in winter as the spring is relatively warm (about 60 degrees). The flow is fairly constant in the winter.

Any suggestions on other types of fish I could put in pond with my rainbow trout, i.e. tilapia.