(SiO2)(n) aggregates flocculated with Al and Fe coagulants were studied. An advanced photographic method for measuring the size and velocity of the aggregates was applied. Fractal dimension D = 1.64-1.95 for 1000 measured aggregates at mean determination coefficient r(2) = 0.940 was calculated. A high variety of "solid mass" contributions (a relative smc ranged from 1 to 18.5) to the total mass of the average sludge were ascertained. Some implications of the process of aggregations studied were supplied. Fractal dimension was recognized as a powerful tool in any aggregate approach, being sensitive enough to distinguish many subtle varieties.