PURPOSE: To perform with no harm for human body effective countermeasure treatment against heat exchanger trouble by introducing a special substance to the brine which is mainly composed of plopylene glycol.

CONSTITUTION: A chelating agent with no harm for human body such as an ethylenediamine desodium tetraacetate (EDTA) and the like is introduced into the brine which is mainly composed of a plopyleneglycol. Further, the purpose is achieved by introducing an antibiotics for the designated fungus according to the requirement. A metal bivalent cation in the brine is fully dissolved and not deposited as a water soluble chelate compound with the EDTA. The antibiotics group of a penicillin family and a cephalos polyyne family is effective for pasteurization or inhibition of prolification against a group such as a staphylococcus, a pseudomonas a bacillus and the like detected in the brine. The introducing of EDTA in an intermediate treatment is effective when a hardness component is easily separated out in high temprature time, for instance, in summer. Also the introducing of the antibiotics can be avoided from useless and effective when the fungus is easily propagated, in medium temperature time, for instance, in spring and autumn.