Composition for use in a water tank in the kitchen or sanitary sector,
characterized by a basic composition essentially evolving its function
following addition to a first water filling of the water tank, in the form
of a tablet and at least one particle, with at least one core, which
comprises at least one substance evolving its function essentially
following an at least partial emptying of the first water filling from the
water tank and the inflow of fresh water and a covering substantially
completely surrounding the core or cores comprising at least one compound,
whose solubility increases with decreasing concentration of a specific ion
in the surrounding medium, the at least one particle being so arranged in
or on the tablet that the surface of the particle or particles is at most
only partly in direct contact with the surface of the basic composition
surrounding the same and the concentration of the specific ion in the
local environment of the particle or particles is sufficiently high up to
a substantially complete dissolving of the tablet in order to prevent a
substantial dissolving of the covering or a substantial detachment of the
covering from the core or cores.
