Because it is cogulat io noprachupwok. If you enter more Colloid negative charge can change into prachubuak. Called a Charge reversal makes colloid prachubuak drive. Colloid stability comes back again.
Since cogulat a positively charged ion. If you enter more Colloids can be converted into anionic, cationic, has called Charge reversal makes colloidal cationic push themselves. Stable colloidal back again.
Because cogulat is ion positive charge if put too much. Anionic colloid can change a positive charge, called Charge reversal makes colloid cation push each other. Colloid stability is back again.