Pond Boss Forums GENERAL QUESTIONS Help Aluminium sulpahte + aereation + algae bloom

I wouldn't use aluminum sulphate. It is considered to possibly be a toxin and will make your water more acidic which in turn could kill organisms and fish. I would check my salinity. Being that it is an old quarry. But your ph and dissolved oxygen look good. Usually proper aeration will keep the algae bloom under control. Maybe test water for hydrogen sulfide or sulfuric gas basically. And usually phosphates are expressed in ppm so I'm not familiar with mg/l. But does seem little high.