I presume you mean the remedial cleaning process to restore a water system that is fouled with scale, corrosion products, or microbiological biomass due to inadequate or ineffective water treatment.
The traditional cooling tower's cleaning agents may be broadly classified as being acid, alkaline, organic, or solvent cleaners. There is no general or universal cleaner that removes all deposits.
The select ion of a solvent or cleaning agent is based on the material's ability to remove or dissolve the deposit, as well as on cost considerations,safety hazards, and the effect of the cleaning material on the metals involved. I suggest that you may ask cooling tower vendor cause they know better specializing chemical for cleaning their product than others. Thanks.