Black Algae, Chlorinator

Opening up pool this spring, added about 10 lbs of stabilizer to my 29,000 gallon pool. Could not get my chlorinator to read the correct amount of salt and didn't register as any stabilizer. No chlorine made. Got black algae which I have treated four times and think is pretty much gone. Now, still don't register any stabilizer after adding another 5 pounds. T. chlorine < 1, Free chlorine 0, PH 7.4, T. Alkalinity 180, Sabilizer 0-20, Salt by test strip 3000 ((chlorinator registers 2000, low salt, solid inspect cell light). Milky water, can't see bottom in 6 ft. At a loss as to where to go with all of this. No problems the last two years. Any help would be greatly appreciated!