Aluminum Chlorohydrate is one of the highest concentrated and most highly charged polyaluminum chlorides available (inorganic). For coalescing electrically charged particles you need highly charged agents. For those of you wondering, the term flocculating refers to the use of polymeric electrolytes (organic backbones)to produce a larger and hence "insoluble" particle held together by Van der Waals and electrostatic forces that in the absence of any physical agitation will fall to the bottom of the water column. The biggest issue, I would imagine, is one of cost per acre-foot of treatment.

Robert, what are you paying for the ACH that you use to coalesce phosphates?

P.S. Most of us, I hope, use ACH on a daily basis. ACH is an important ingredient in some antiperspirants/deodorants. The electrolyte chemistry of ACH in the presence of perspiration allows the formation of a gel that temporarily stops up sweat glands and reduces perspiration. The low pH kills off odor-causing bacteria...