IMO it's time to put the chemicals on the shelf; place the diffusers in the deepest water at 2 ft. off the bottom to prevent stirring up the stuff, and give the aeration time to dissipate the excessive nutrients. It didnt happen overnight and will not be cured overnight. Let the O2 and aerobic bacteria do it's job and enjoy the fish you have. It may take 2 or 3 years for it to get right, but it will happen. For the FA to grow the pond must have been clear early this spring. Correct, or no? Usually sunlight must reach the bottom for FA to get going good.
Not knowing your water chemistry or the reason for the staining, or if it would have settled on it's own; cant say whether you even need alum, or how much. What is your depth of visibility? How about hardness, alkalinity, average ph? Have you done a jar test to see if the stain settles in 24 hrs. or if a specific amount of alum will settle it? Any feed and garden store should have aluminum sulphate enough to do the testing with.
Is this the pond with the rough fish in it?
I have been raking the FA out of my pond as the wind or aerator pushes it to the edges. I just put on the higher rated pump 2 wks. ago and it has caused the FA to start dieing. I will definitely start 24/7 aeration earlier next spring and possibly put in a little die after winter rains and clear water. My nutrients are high because it's full of fish now.
