I remember Meadowlark has stated that it took more than one season of Tilapia to get his FA fully under control, and that he used chemicals the first year (or two?) in conjunction with the Tilapia.
This made it seem to me that FA control with Tilapia can be a progressive thing, beating the algae back some each year and leaving a smaller residual amount of FA to start up again the following year.
If your FA situation seems better now than at the same time (and weather) last year, I think would be an indication that you and your Tilapia are making progress.
I'm sure ML will add much more detail.
"Live like you'll die tomorrow, but manage your grass like you'll live forever." -S. M. Stirling