My results with Tilapia was not that the young would not eat the FA, but that I didn't stock enough. I think in southern ponds you can get by with stocking less of the larger more expensive ones because in the longer growing season the stockers will thousands of babies, maybe once maybe more than once in a long hot Texas summer? It is the multiplication of thousands that work well to trim back on the FA as Fishingadventure describes above.
In my case due to short warm weather season the stockers did not make babies so it was only the initial stockers vs the algae. The adult TP also eat other things besides FA like bugs and even little fish so not all their diet was towards the FA.
I stocked 3-4" stockers and didn't weight them but was probably close to 10 pounds in a quarter acre puddle so close to 40#/acre. They didn't make a sizable dent in the FA. That means that I probably would have to stock many more. It would be ideal if I could bring a tank inside and see if a few breeding pairs could produce thousands of young TP to go in the pond once weather warms up in the spring but I'm not set up or have the know how to keep a tank of fish alive all winter inside.
Aquaponics is not a big hobby or industry here so we struggle to source the TP as well.