We studied the influence of the arrays of ceramic balls on the hardness of
water and discovered effects, which can possibly explain the correlation between the
balls and the growth of calcite crystals of CaCO_{3}. A model to compute the electric field
at the surface of the balls is proposed. It is shown that the number of polarised nuclei
contributing to scale prevention is considerably larger than in natural water. Numerical
simulations for a two-dimensional macroscopic model show that the effect of ceramic
balls can be reproduced in configurations studied experimentally and industrially. Summarising, we note that ceramic balls induce a polarisation in the calcite particles thus
decreasing the surface tension energy of crystals in the vicinity of the ceramic balls.