How to Convert a Chlorine or Salt Pool to a Natural Pool

Converting a traditional chlorine or saltwater pool into a natural swimming pool — also called a biopool or living pool — is more achievable than most homeowners realise. By combining modern filtration technology with biological plant systems, an existing chemical pool can be re-engineered to sustain crystal-clear, chemical-free water. This guide outlines the key planning steps, equipment options, and conversion processes used in professional retrofits.

Step 1 — Planning and suitability assessment

Before beginning the conversion, assess the pool's structure, hydraulics, and environment. A sound concrete or lined shell is essential, as is good circulation infrastructure. Key assessments:

• Structural integrity — inspect for cracks, leaks or delamination that must be addressed before conversion
• Existing hydraulics — review the pump, filter and plumbing for compatibility with low-pressure continuous-flow biological systems
• Site factors — assess sun exposure, leaf load, bather frequency and available space for any regeneration zone expansion
• Water source — test source water for phosphate and mineral content, which affects filtration sizing

These factors determine which conversion approach is most appropriate and what filtration capacity the system will need.

Step 2 — Three conversion approaches

Step 3 — Equipment and circulation

Reliable, continuous circulation is vital for clarity and biological health. A natural conversion typically requires:

• Variable-speed pump — low-pressure, continuous operation at reduced energy consumption
• Bead or glass-media filter — mechanical pre-filtration to capture solids before biological processing
• UV-C steriliser — eliminates pathogens and algae spores in the circulating water
• Biological chamber or biofilm media — where beneficial bacteria colonise and perform nutrient conversion
• Phosphate filter — optional but highly effective in reducing nutrient load, particularly with mineral-rich source water

Step 4 — Media and planting

For regeneration zones, use layered stone media: 20–40mm base drainage layer, 8–16mm filter layer, and 2–8mm top layer. Avoid fine sands, which clog rapidly.

Select native or climate-tolerant aquatic species: hornwort, iris, rush, reeds, lilies or lotus depending on your climate. These plants oxygenate the water, stabilise nutrients and create a balanced ecosystem that supports long-term clarity.

Beyond filtration, even a small planted zone or perimeter planter softens concrete lines, blends the pool into its natural surroundings and transforms a sterile basin into a vibrant, living landscape feature.

Step-by-step conversion workflow

1. Deactivate the chlorine system — disconnect or isolate salt cells or chlorinators; let residual chlorine dissipate over several days
2. Clean and inspect — remove scaling, biofilm and debris; repair any cracks or leaks
3. Reconfigure hydraulics — connect: pump → prefilter → mechanical filter → UV-C → biological or phosphate filter → returns
4. Install new filtration components — whether a converter module or planted wetland, ensure even water distribution and easy maintenance access
5. Add plants and fill the system — introduce aquatic plants carefully, using clean water and avoiding turbulence that uproots young roots
6. Start continuous circulation — let the system run 24/7 during early stabilisation (typically 6–10 weeks); expect some natural algae bloom before biological balance establishes

Ongoing maintenance and operation

Run the pump continuously during the swimming season and reduce speed in cooler months — never let the system stagnate. Backwash mechanical filters as needed, replace UV-C lamps annually, and trim aquatic vegetation seasonally. Keep phosphate levels below 0.03 mg/L to prevent algae growth.

A well-maintained converted system stays clear year-round with minimal intervention — typically less effort than the chemical balancing routine of the original pool.