Spencer,
Just reading in on the topic, my suggestion to resolve your issue would be to install an aeration system with two diffuser stations as recommended above, one placed in the at or near the deepest part of the pond, while placing the other in the deepest part of the cove. Algae is a symptom of your problem, so I would suggest focusing on the problem, which is the available nutrients within your pond.
Aeration is likely the solution to much of your frustration, so I suggest not cutting any corners, even it if takes away from other projects you were planing on paying for in 2010. Install a aerator that is over sized for a 3/4 acre pond. I would recommend and equivalent to a Vertex Air 2 or *Air 3*, which ever size your budget will allow. The headache and treatment savings along with the increase in biomass your pond can support will be worth the investment.
My experience with Grass Carp has had little success with algae removal, so I would stick with the Tilapia, but you may find that algae is not an issue once you have sufficient aeration, especially if you promote phytoplankton to utilize the available nutrients. Install the aeration prior to the warm season if possible, otherwise you will likely feed your algae even more and have a frustrating spring. Getting your pond where you want it may take some precision, so if your alkalinity is low, lime, then once aeration is installed treat your algae in the spring to eliminate it and add some phytoplankton to give the plankton a jump start.
