Anti-bacterial machine and tank wash is not something you do on the calendar. You do it when the coolant is telling you it is time. The rest is money you did not need to spend.
Signs the sump wants a wash
- pH creeping below 8.6 and refusing to come back up with a top-up.
- Rotten-egg smell first thing on a Monday, gone by mid-shift. That is anaerobic activity in the low-flow zones of the tank.
- Dermatitis reports from the operators. That one is not optional. Book the wash.
Signs the sump is fine
- Refractometer reading holding steady week to week.
- Skimmed tramp oil coming off cleanly and consistently.
- No visible biofilm on the return pipe when you dip a torch in.
What a proper wash includes
If it is scheduled, the job we quote covers: pump-out, mechanical clean of the tank walls, chase every dead-leg with the sanitiser, refill and re-inhibit, and a follow-up refractometer check at 48 hours to confirm the ratio held. Anything less is a rinse, not a wash.
The shortest-lived washes we see are the ones where the tank got cleaned but the machine bed did not, so the biofilm was seeded back in on the first cycle.
