This model, although somewhat different than the conventional theory, explains why silica is not removed by salt form anion resins. Silica, once exchanged onto the resin, is still able to polymerize. pH drops in the resin as it exhausts, encouraging polymerization or dumping. Polymerized silica probably stays on the resin, while monomeric silica dumps. In the desilicizer example, the high pH prevented silica polymerization and allowed dumping to occur. Two bed demineralizers do not dump silica as easily as mixed beds due to the lower pH at the inlet to the anion exchanger.