Alum - where to buy?

[mbar]

I'm not sure if this is what you are looking for, but here is a link:
http://www.chemistrystore.com/alum.htm

[waterbear]

Auminum Sulfate is an effective flock but be aware that if there are phosphates in the water it can cause the water to get very cloudy as the phosphates precipitate out. It can take a day or two for it to settle and then you must vacumn to waste. Alum is not a good idea if the pool has a cartridge filter.

[tonyl]

I get mine at Leslies

[CarlD]

I used a floc once 7 years ago. Haven't since. I suppose if a pool is a mess and you've gone through ALL the steps to clean of high chlorine, 24/7 filtering etc. and it you might need it.