Chad Todd hits a very important point that Bob often stresses. The timing of the plant control and fertilization is critical. Reduce the bad plants and then quickly get a bloom to shade them out.
If the problem is in the 30 acre lake and also some in the 7 acre lake then you might want to look at a Jensen lake mower.
to Annamarie at
[email protected] ,
http://www.lakemower.com/ A tilapia growout pond will out produce a BG pond (forage weight) by several factors if the conditions are right. You will be moving a lot of fish. See if Todd can help.