Optional Mineral Support

Surface Biofilm Management During Peak Summer

Every Leaf & Stone pool is engineered to function biologically. Water clarity is achieved through circulation, filtration, and biological balance — not chemicals. However, in warm summer conditions, even well-balanced biological pools can develop a fine surface biofilm or light algae dust on walls and steps. This is natural biology at work.

In pure biological mode, this simply means:

  • Weekly brushing, or

  • Regular robotic cleaning during peak season

For some clients, this is perfectly acceptable. For others, especially those accustomed to chlorine pools where surfaces remain largely sterile, this extra maintenance is undesirable. For that reason, we offer an optional mineral support strategy.

What Mineral Support Does

Trace copper (typically 0.2–0.5 mg/L) is introduced seasonally to suppress surface biofilm formation. The goal is not water clarity — clarity is already engineered into the system.

The goal is:

  • Reduced wall brushing

  • Reduced robotic cleaning

  • Cleaner-feeling surfaces

  • A maintenance profile closer to that of a chlorine pool

  • Without using chlorine or oxidising chemicals

It is a performance option, not a requirement.

How Much Copper Is Used?

The concentration we operate at is below international drinking water standards.

For reference:

  • WHO guideline for drinking water: 2.0 mg/L

  • US EPA action level: 1.3 mg/L

  • Our operating range: 0.2–0.5 mg/L

This is controlled, trace-level mineral dosing. A 30,000-litre pool at 0.3 mg/L contains approximately 9 grams of copper in total.

A Note on Environmental Context

Copper is a naturally occurring mineral.

It is widely used in:

  • Organic agriculture (approved in controlled quantities as a fungal suppressant)

  • Drinking water plumbing systems

  • Marine anti-fouling technologies

In a pool system:

  • Most copper binds to filtration media and surfaces

  • It does not biomagnify through food chains

  • When discharged to wastewater treatment, it binds to solids and is captured in sludge

  • In soil, it binds strongly to organic matter and has low mobility

The environmental footprint of trace, seasonal use in a contained swimming system is modest and localised.

Two Operating Modes

You can choose:

Pure Biological Operation

  • 100% natural filtration

  • Slightly higher summer maintenance

  • Maximum ecological purity

Seasonal Mineral Support

  • All biological filtration retained

  • Trace copper used in summer

  • Reduced surface maintenance

  • Comparable surface cleanliness to chlorine pools

  • Still chlorine-free

Our Philosophy

We design ecological systems first. Mineral support is simply an optional layer for clients who prioritise reduced maintenance during peak swimming season.

The choice is yours.