How often should I dose?

Once per week as preventative maintenance in hard-water areas.

Water with total hardness above 200 ppm. Most of southern and central England is in this band.

Will it remove existing scale?

It will slowly dissolve light scale over weeks. Heavy scale needs descaling at the next water change.

How long does 1 L last?

Around 6 months of weekly dosing for a 1500 L hot tub.

Is it safe for salt-water systems?

Yes. It protects salt chlorinator cells, which are particularly prone to scaling.

Do I still need to balance calcium?

Yes. The inhibitor prevents scale formation but does not replace calcium balancing.

What is the active chemistry?

A blend of organophosphonate (HEDP family) and a low-MW polymer for crystal modification.

Does it raise phosphates?

Slightly. 10 ml per 1000 L adds about 1-2 ppm phosphate, well below algae-feeding thresholds for hot tubs.

Will it interfere with sanitiser?

No. The phosphonate is inert to chlorine, bromine and MPS at recommended doses.

Calcium hardness is above 400 ppm or pH above 7.8; refresh water and rebalance.

Cloudy water after dosing?

Existing scale dissolving; run filter 24 hours and clean cartridge.

pH drift after dosing?

Mild alkali shift; dose pH minus to return to 7.4.

Scale inhibitor vs descaler?

Inhibitor prevents new scale and slowly removes light deposits. Descaler is a strong acid product used during a water change to remove heavy scale.

Scale inhibitor vs lowering calcium?

Lowering calcium below 150 ppm causes corrosion. The inhibitor lets you hold safe 200-250 ppm hardness while still preventing scale.

Water Scale Inhibitor

Name: Water Scale Inhibitor
Brand: ClearSpa
SKU: we-3
Availability: InStock
Rating: 4.5 (6 reviews)

Block calcium scale on heaters, jets and waterlines before it forms. A weekly low-dose phosphonate that holds calcium in solution even in hard-water areas.

Holds calcium and magnesium in solution to prevent scale.
Protects heater elements, jet faces and waterline tiles.
Restores flow on slightly scaled equipment over time.
Compatible with chlorine, bromine, MPS and salt systems.
Designed for hard-water areas with TH above 250 ppm.