More alum is needed. Keep applying it until you see the clay particles start to form clumps and settle out to the bottom of the pond. Keep an eye on the pH.
Brian, in my pond I drove a galvanized pipe (3/4") into the pond bottom. Then I bought a 6' powdercoated aluminum "ruler" from Lowes. I zip tied it to the pipe. It reads backwards, but I can tell how many inches the pond raised or lowered. It does get some growth on it, but a white non-scratching scotchbrite scrubbing pad cleans it off easily when it's still wet.
In my pond, a 3' yardstick isn't big enough to measure the water fluctuation.
