One concern is the level of chips, fines or swarf in the sump. Quantities of these small particles can provide an enormous surface area for bacteria to attach themselves, while at the same time creating “dead areas” where coolant cannot circulate. The easiest means to control solids is to clean out the sump on a regular basis and use some type of filtration.
Use a proportioning device to ensure proper mixing of coolant with water. Accurately and thorough mixing of the coolant with water is imperative. As a rule of thumb, run makeup concentration 60% as strong as initial charge, to compensate for evaporative losses. Never add coolant concentrate directly into the coolant sump.
For each sump or system, maintain a record of coolant and water additions, as well as any testing results. This will ensure that product is being properly maintained and will help identify trends such as evaporation and makeup rates for the system.