Alum isn't a "lets put a little in to clear the water a little". You have to put in enough to start the clay flocculation or it's like you didn't add any at all.
By doing the bucket test, that should have told you how much alum you needed to start the flocculation process.
High pH or not, keep testing as you go and have some Hydrated lime on hand. That is unless you don't have fish in there. Then it doesn't matter.
That alum that you added, how much did it change the pH?
