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What Size Salt Chlorinator Do I Need?
Quick answer: Salt chlorinators are sized by their chlorine output rating (grams per hour), not pool volume directly. As a planning guide: an 18 g/hr cell typically suits pools up to about 30,000 L, 26 g/hr up to about 50,000 L, 35 g/hr up to about 70,000 L, and 45 g/hr and above for 90,000 L or larger. Always check the specific model's rated pool size — output bands vary between brands, and running a chlorinator near the top of its rated range shortens cell life.
How salt chlorinator sizing actually works
A salt chlorinator generates chlorine by passing pool water containing dissolved salt over an electrolytic cell. The cell's output — how many grams of chlorine it can generate per hour of run time — is fixed by its size and design, so sizing a chlorinator means matching that output rating to your pool volume, bather load, and climate, rather than picking a number that happens to equal your pool's litres.
A cell running near the ceiling of its rated range every day works harder and typically needs replacing sooner than one with headroom. If your pool volume sits right on the boundary between two output bands, the larger cell is usually the better long-term choice for cell life, even though the chlorinator itself costs more upfront.
Typical output bands by pool volume
| Pool volume | Typical output rating | Notes |
|---|---|---|
| Up to 30,000 L | ~18 g/hr | Entry-level residential cell |
| Up to 50,000 L | ~26 g/hr | Most common size for standard Australian in-ground pools |
| Up to 70,000 L | ~35 g/hr | Larger pools or higher bather load |
| 90,000 L and above | ~45 g/hr+ | Large pools, or pools wanting extra headroom for hot climates |
Treat these as planning bands rather than exact figures — every brand publishes its own rated pool size per model, so confirm the specific unit's rating before buying.
What pushes you toward the bigger cell
Climate and UV exposure. Chlorine burns off faster under strong sun and in hot climates, so pools in harsher UV conditions often run their chlorinator on a higher output setting more of the time — extra headroom means the cell isn't maxed out to keep up.
Bather load. Frequent swimming, parties, and high usage increase chlorine demand. A cell sized exactly to your pool's minimum requirement leaves no buffer for busy periods.
Stabiliser (CYA) level. As with manual dosing, higher cyanuric acid levels reduce the effective sanitising power of a given chlorine output, which can mean running the chlorinator harder to hold the same free chlorine reading.
Salt level requirements
Required salt concentration varies significantly by chlorinator design — low-salt systems are commonly designed to run in roughly the 2,000–3,000 ppm range, while traditional salt chlorinators typically need somewhere in the 4,000–6,000 ppm range to operate correctly. Running below the minimum salt level for your specific model reduces output and can trigger a low-salt warning; running well above the maximum can accelerate cell wear. Always dose to the salt range printed on your unit, not a generic figure, and test salt level periodically rather than assuming it stays constant — splash-out, backwashing, and rain all dilute it over time.
Cell life and replacement
Most chlorinator cells are rated for roughly 3–5 years or a set number of run hours, whichever comes first, though actual life depends heavily on water balance, salt level accuracy, and how close to maximum output the cell runs day to day. A cell that's undersized for the pool and constantly maxed out will generally wear out faster than a correctly sized or slightly oversized one. Declining chlorine output despite correct salt level and settings is the usual sign a cell is nearing end of life.
FAQ
What size chlorinator do I need for a 50,000 litre pool? Around 26 g/hr output is the typical band for a 50,000 L pool under normal conditions, though hot climates or high bather load may justify sizing up to the next band for headroom.
Can I oversize a salt chlorinator? Yes, and it's generally a safe choice — an oversized cell runs at a lower percentage of its maximum output to hit the same chlorine target, which typically extends cell life rather than causing any downside.
How much salt do I need to add? It depends entirely on your specific chlorinator's rated range, which can vary from roughly 2,000 ppm to 6,000 ppm depending on the model — check your unit's manual or rating plate and test before topping up rather than guessing.
How long do salt chlorinator cells last? Typically 3–5 years with correct salt level and normal use, though a cell run consistently near its maximum output or outside its rated salt range will usually wear out sooner.
Why is my chlorinator not producing enough chlorine? The most common causes are low salt level, a cell nearing end of life, or a chlorinator that was undersized for the pool in the first place and has no headroom left to increase output.