Pool Cyanuric Acid Dose
Calculator
Results
- Increase needed (ppm)
- 30
- Active stabiliser needed (g)
- 1,500
- Product to add (g)
- 1,500
- Product to add (kg)
- 1.5
Pool and aquarium results
| Increase needed (ppm) | 30 |
| Active stabiliser needed (g) | 1,500 |
| Product to add (g) | 1,500 |
| Product to add (kg) | 1.5 |
formula-map diagram
- Increase needed (ppm)
- 30
- Active stabiliser needed (g)
- 1,500
- Product to add (g)
- 1,500
- Product to add (kg)
- 1.5
Pool and aquarium relationship
Formula
product = (target − current) × volume(m³) ÷ (strength ÷ 100)= 30
Note
This is a simplified model: it applies a standard geometric or physical formula to the numbers you entered. Volumes assume a regular shape and an even average depth, and the kidney shape uses the common 0.45 × (A + B) × L area approximation. Chemical doses convert a target change into a product mass using the strength or label dose you enter, because the amount of active ingredient varies from product to product; they ignore pH, temperature, buffering, sunlight, bather load and existing chemical interactions. Heating uses Q = m × c × ΔT with c = 4186 J/kg·K and ignores heat losses to air, ground and evaporation; evaporation and cover figures use the rate you enter, not local weather. Aquarium stocking by surface area is a rule of thumb, not a biological limit. Always follow the product label and test the water before and after dosing, and consult a pool or aquarium professional for anything you are unsure about.
More in Pool and aquarium
See all →Frequently asked questions
What does cyanuric acid do, and why does the pool need it at all?+
Cyanuric acid (stabilizer or conditioner) shields chlorine from rapid breakdown by UV sunlight; without it, an outdoor pool can lose most of its free chlorine within a couple of hours on a sunny day. The calculator doses toward the standard target of 30-50 ppm, which meaningfully extends chlorine's working lifespan without overdoing it.
What is 'chlorine lock' and is it something to worry about?+
Chlorine lock is a popular but technically imprecise term for what happens when cyanuric acid is too high (often above 100 ppm): chlorine is so heavily bound that its effective sanitizing power drops sharply even though a test kit still reads a normal free chlorine number. It's a real practical problem, just not literally a total lock — more chlorine is still needed to compensate, or the level must be diluted down.
Why can't I lower cyanuric acid with a chemical the way I lower pH or alkalinity?+
There is no chemical that selectively removes cyanuric acid from pool water; the only ways to reduce it are partial or full water replacement, or specialized (and often costly) reverse-osmosis filtration. This is why the calculator emphasizes not overdosing in the first place — prevention is much cheaper than correction.
Does an indoor pool or a saltwater pool need cyanuric acid?+
Indoor pools generally don't, since there's no UV sunlight degrading chlorine; adding stabilizer there just risks pushing levels too high with no benefit. Saltwater pools generate chlorine via electrolysis but that chlorine is still just as vulnerable to sunlight, so cyanuric acid is just as necessary outdoors in a salt system as in a traditionally chlorinated one.
Why does the calculator ask if I'm using stabilized or unstabilized chlorine products?+
Trichlor and dichlor tablets/granules already contain cyanuric acid as part of their chemical structure, so routine use of those products raises stabilizer levels over time even without adding pure cyanuric acid separately. If you use only liquid chlorine (unstabilized) or a salt system, you'll need to dose cyanuric acid directly since it isn't being added as a side effect of sanitizing.