Bill,
I would think you could still use the tilapia, but you probably wouldn't have to restock them every spring like many pond owners. I would keep an eye on their numbers, since they do produce so many offspring. If they get too numerous, or if there aren't enough LMB to keep them in check, then you can always fish for them and/or trap them to adjust the population.
What is your goal for this pond? Trophy LMB? An abundance of BG/RES/CNBG? That will help you decide your next course of action.
I know you are concerned about the algae, but fertilizing the pond might reduce the clarity, thus helping the CNBG reach a size at which they can't be eaten by the 10-13" LMB.
