1 acre pond NE Tx, year 3, deepest 13 feet, 50 acre watershed and spring fed. Last year, paradoxically after I installed bottom diffused aeration, FA problem began. Sprayed gallons of copper on it, raked out tons of it, stopped fertilization: accomplished nothing. This year, put in 10 lbs. of tilapia, still no fertilization, stopped my fish feeder to keep tilapia from getting full on it: accomplished nothing. Tilapia have been in 3 months and FA covers about 75% of pond surface. Is there any hope? What shall I do?