Snowmaking additives are dosed in parts per million — grams of additive per cubic metre of water — and a modern polymer additive works at single digits, around 6–7.6 ppm. At that rate, one cubic metre of snowmaking water carries roughly 6 to 8 grams of active additive, metered in by a dosing pump upstream of the guns. Ppm is the language of the dose because the active loading is genuinely that small.
Operators new to additives are often surprised by how little goes in. The instinct is that changing snow behaviour must take a lot of material. It does not — the chemistry acts on the freezing and recrystallization of water at very low concentrations, which is what makes ppm the right unit and drop-in dosing practical. This explainer covers what ppm means here, how the arithmetic works, how it is metered, and how polymer and biological dose rates compare.
Key takeaways
- Ppm means parts per million by mass: 1 ppm ≈ 1 gram of additive per cubic metre (1,000 litres) of water.
- A polymer snowmaking additive like SL6733 is dosed at roughly 6–7.6 ppm — single-digit grams per cubic metre.
- Dosing is done with a metering pump that injects concentrate into the water main upstream of the guns, proportional to flow.
- Low ppm is why additives are a drop-in: no gun changes, minimal hardware, tiny material volumes per season.
- The residual free acrylamide monomer in a polyacrylamide additive is held to ≤0.05%, keeping the in-water concentration far below drinking-water limits.
What does ppm mean for a snowmaking additive?
Ppm means parts per million by mass — the ratio of additive to water. Because a cubic metre of water is 1,000 litres and weighs about 1,000 kilograms (one million grams), 1 ppm works out to almost exactly 1 gram of additive per cubic metre of water. So a 6–7.6 ppm dose is 6 to 7.6 grams of active additive in every cubic metre pumped through the system.
That unit is not arbitrary. It reflects that the additive acts catalytically on the physics of freezing rather than bulking up the water. A polymer inhibits ice recrystallization and aids nucleation at concentrations where it is a vanishingly small fraction of the mixture — the mechanism is explained in polymer snowmaking additives explained and, at the crystal level, in what ice recrystallization inhibition is. The takeaway for dosing is that effectiveness and concentration are decoupled: you are not trying to saturate the water, you are supplying enough active molecules to change how it freezes.
How do you calculate the additive volume from a ppm dose?
To find how much additive a system uses, multiply the ppm rate by the water volume, then adjust for the concentration of the product you actually pour in. The active-ingredient arithmetic is simple; the practical figure depends on whether the product is supplied neat or as a diluted concentrate.
Worked example, active basis at 7 ppm:
- 1 m³ (1,000 L) of water → 7 g of active additive.
- 1,000 m³ of water → 7 kg.
- A resort pumping, say, 100,000 m³ of water over a season → about 700 kg of active additive for the whole season.
| Water volume | Active additive at 7 ppm | |---|---| | 1 m³ (1,000 L) | 7 g | | 100 m³ | 700 g | | 1,000 m³ | 7 kg | | 100,000 m³ (season, small resort) | 700 kg |
If the product ships as a concentrate — say a solution that is a defined percentage active — you scale the poured volume up accordingly, and the dosing pump is calibrated to deliver the target active ppm at the measured water flow. The season-scale material figures are small precisely because the dose is single-digit ppm, which is part of why the logistics and storage footprint of an additive are modest compared with the capex of equipment-based alternatives; that comparison is in snowmaking additive vs all-weather snow machine.
How is the additive actually metered into the system?
The additive is injected by a metering (dosing) pump into the water main upstream of the snow guns, proportional to water flow, so the ppm stays constant as flow varies. The dosing skid is a small piece of hardware — a pump, a concentrate tank, an injection point, and flow-proportional control — installed on the supply side, not at each gun.
- Flow-proportional dosing. The pump reads water flow and adjusts injection so the concentration holds at target ppm whether one gun or fifty are running.
- Upstream injection. Because the additive acts in the water, it is dosed once into the main, then distributed to every gun on that line — there is no per-gun modification.
- Drop-in installation. No change to guns, nozzles, or compressors. This is the core reason an additive is not a capex retrofit: it complements any snow gun, fan or tower or lance.
That drop-in property is a real commercial advantage. An operator keeps existing equipment and adds a chemistry layer, rather than replacing hardware. It is also why an additive stacks cleanly with the other efficiency levers in how to reduce snowmaking costs.
How does polymer dosing compare with biological nucleant dosing?
Polymer additives and biological nucleants are both dosed at low ppm, but they do different jobs, so the dose is not directly comparable. A biological nucleant supplies ice-nucleation-active protein to raise the freezing temperature; a polymer additive inhibits recrystallization and aids water retention. Comparing them by ppm alone misses that they act on different parts of the process.
| Additive type | Mechanism | Typical dose | Regulatory frame | |---|---|---|---| | Biological nucleant (e.g. Snomax) | Ice nucleation — raises freezing temperature | Low ppm | Assessed as biological; restricted in several Alpine markets | | Polymer additive (e.g. SL6733) | Recrystallization inhibition + nucleation + water retention | ~6–7.6 ppm | Assessed as a chemical under REACH / TSCA | | Surfactant (e.g. Drift) | Wetting / nucleation aid | Low single-digit ppm | Assessed as a chemical |
The regulatory column matters as much as the mechanism. A biological product is assessed as a biological — the framework behind the national restrictions on Snomax — while a synthetic polymer is assessed as a chemical, a different and, in the addressable markets, more durable pathway. The mechanism-and-pathway contrast is drawn out in biological vs chemical snow additives.
Is a ppm-dosed additive safe in the water?
At single-digit ppm, and with the regulated impurity held to a strict ceiling, a polyacrylamide additive sits far inside water-safety limits. For polyacrylamide the parameter that matters is not the polymer — which is large and inert — but the residual free acrylamide monomer, held to ≤0.05% of the polymer. That ceiling, combined with ppm dosing, puts the in-water acrylamide concentration orders of magnitude below regulatory thresholds.
The USDA NRCS standard for anionic polyacrylamide sets the ≤0.05% residual-monomer level for irrigation water, and the EU Drinking Water Directive limits acrylamide in potable water to 0.1 µg/L — a limit a ppm-dosed, low-residual product stays well within. Polyacrylamide is not readily biodegradable, but it is non-bioaccumulative, low in aquatic toxicity, and carries a decades-long agricultural water-use record; the honest full picture is in is polyacrylamide biodegradable. Every functional claim stays physical — nucleation, recrystallization inhibition, water retention — which keeps the product assessed as a chemical rather than a biocide.
What ppm should an operator target?
The target ppm is the manufacturer's specified operational range for the specific product and conditions — for a two-component polymer additive like SL6733 that is roughly 6–7.6 ppm. The right figure balances performance against material use, and it should come from the vendor's spec and, ideally, pilot data from conditions like yours rather than from a rule of thumb.
Practical guidance:
- Start from the spec range, not a guess — dose to the manufacturer's operational ppm.
- Calibrate the pump to water flow so the concentration holds across varying gun counts.
- Confirm the residual acrylamide figure (≤0.05%) and the concentrate's active percentage before calculating poured volume.
- Validate under your conditions — treat headline performance as modelled until a pilot confirms it on your water and at your wet-bulb.
Where SL6733 sits
SL6733 is a two-component polymer additive — an anionic poly(acrylamide-co-sodium acrylate) for recrystallization inhibition plus a cold-water-swelling starch nucleant — dosed at 6–7.6 ppm as a flow-proportional, drop-in injection into the water main. The modest material volumes and drop-in dosing are part of why it is priced on the value it creates rather than as a commodity; the product detail is in what is SL6733.
If you want the ppm arithmetic and dosing hardware mapped onto your own system and water volumes, request a pilot or send us a message.
SL6733 is pre-commercial, with EU lab pilots targeted for the 2026/27 season; dose rates cited are the specified operational range and any performance outcome is modelled until validated under pilot conditions. Water-safety figures are drawn from the referenced standards and are not legal advice.