Assess scale before cleaning
- Scope
- Assess the deposits and system materials before agreeing an acid cleaning scope.
- Before you enquire
- Deposit condition, materials, access and possible downtime.
- Quotation and scheduling
- The quotation identifies agreed work, tests and records. Price and scheduling depend on the system, access and any required downtime.
- Next step
- We reply within one working day, then confirm the scope and whether a site assessment is needed.
Acid cleaning removes hardness scale from a cooling tower's fill and wetted surfaces without dismantling anything. A descaling chemical is dosed into the basin and recirculated through spray pipes over each fill partition for 4 to 6 hours, then neutralised and rinsed away. Routine cleaning and disinfection removes sludge and controls Legionella; it does not dissolve hard scale. Scaled fill stops air and water meeting properly, so the tower loses capacity and the chiller works harder.
When a tower needs acid cleaning
Scale builds where water evaporates: on the fill, the hot deck and the wetted surfaces below the spray. Once it is there, a routine clean will not shift it. Signs that a tower is due for acid cleaning:
- White or grey deposit visible on the fill and hot deck, hard to the touch rather than slimy.
- Approach temperature or condenser head pressure creeping up while the fill looks crusted.
- A period without scale inhibitor, or running at high cycles of concentration.
- A routine clean and disinfection that left the fill clean of sludge but still hard and pale.
If you are not sure, send us a photo of the fill and we will tell you whether it is scale or dirt.
How it differs from routine cleaning
| Routine cleaning & disinfection | Acid cleaning | |
|---|---|---|
| Purpose | Legionella control and sludge removal under the EMSD Code of Practice | Removing hardness scale from the fill and wetted surfaces |
| What it removes | Sludge, biofilm and loose deposit | Calcium carbonate scale bonded to the fill |
| Chemicals | Disinfectant | Inhibited acid descaler, then a neutraliser |
| When | On the routine schedule the Code of Practice sets | When scale is present, as a separate job |
| Tower status | Offline for the clean | Offline: 4–6 hours of recirculation plus set-up, neutralising and rinsing |
One does not replace the other. A scaled tower still needs its routine cleaning and disinfection on schedule.
What happens on site
- Place a submersible pump in the cooling tower basin with a PVC outlet.
- Remove the access panels on top of each partition of the tower.
- Install a perforated PVC spray pipe over each partition, through the access panels.
- Connect the pump outlet to the spray pipes with a flexible hose.
- Check the basin has enough water, then dose the cleaning chemicals directly into the basin.
- Run the pump and recirculate the cleaning chemicals through the tower for 4 to 6 hours.
- Neutralise, drain and rinse, then refill and restart the normal treatment programme.
- Report — a dated record of the chemicals used and the condition of the fill.
The chemicals we use
All from our own cleaner and descaler range, chosen after we have looked at the tower's materials:
- Freshol 9300 — liquid acid scale remover with built-in corrosion inhibitors and a colour indicator.
- Freshol 98 — powdered weak-acid scale remover with corrosion inhibitor, easier to handle on site.
- Freshol 2000 — neutralises the acid after cleaning and stabilises hardness so scale does not re-form straight away.
What you get back
- Cleaner fill surfaces and proper air–water contact, so the tower cools as designed.
- Less fan and chiller energy for the same cooling duty.
- Less make-up water and treatment chemical wasted on a fouled system.
- A tower that holds its treatment programme afterwards, because the inhibitor is protecting clean metal rather than deposit.
Acid cleaning fixes the scale that is already there. Keeping it away is the job of the treatment programme: scale inhibitor, the right cycles of concentration and routine testing.
Safety and the building
The descalers we use are inhibited to protect the tower's metal, the tower is isolated and offline throughout, our technicians work in the protective equipment the safety data sheet specifies, and the spent solution is neutralised before it is drained. Waste is handled as the property management office instructs.
Frequently asked questions
How long does cooling tower acid cleaning take?
The recirculation itself runs 4 to 6 hours. With set-up, neutralising, rinsing and refilling it is normally a single day's work, with the tower offline throughout.
Do you have to remove the fill?
No. The descaler is sprayed over each fill partition through perforated pipes fitted via the top access panels, so the fill is cleaned in place.
Is acid cleaning the same as the routine cleaning the EMSD Code of Practice requires?
No. The Code's routine cleaning and disinfection deals with sludge and Legionella. Acid cleaning is an extra job for hardness scale, done when scale is present, and it does not replace the routine schedule.
Will the acid damage the tower?
The descalers we use carry built-in corrosion inhibitors, the solution is neutralised afterwards, and we check the tower and pipework materials before choosing the product. Where acid is not appropriate we use a neutral cleaner instead.
How do I know if my fill is scaled rather than just dirty?
Scale is hard, pale and bonded to the fill; dirt and biofilm wipe off. A rising approach temperature with a fill that looks crusted usually means scale. Send us a photo and we will tell you.
Scope and records
The agreed quotation defines the work, analysis, deliverables and schedule.
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Scale on the fill?
Send a photo on WhatsApp. We will tell you whether acid cleaning is the right job and quote it after a free site visit.