I agree. If you have TFS you do not need GShad with your goal. They do compete with each other if plankton is limited. FWIW there are studies that show TFS can supress Gshad in some situations. In unfertile ponds both also compete with young BG. IMO you will get more for your $ feeding BG in your situation. If you could use the other pond to grow and source BG that would be great. Water needs to be fertile for either Gshad or TFS.