POOL CHEMISTRY CALCULATOR
ClearPool
Pool Chemistry Calculator
You have a reading. ClearPool tells you what to pour in.
Type the numbers off your test kit and the app works out which chemical to add and how much of it for your pool's actual volume — chlorine, acid, baking soda, calcium, stabiliser or salt. Pools and hot tubs, on the phone, with no account.
Free to use. $4.99 one-time unlock.
Android and iOS.
The dosing screen, as it ships
One reading in, five instructions out
A 19,200-gallon in-ground pool, tested on a Saturday morning. The left column is what you type. The right column is what ClearPool hands back, in the units you chose.
YOUR TEST
- Volume
- 19,200 gal
- Free chlorine
- 3.0 ppm
- pH
- 7.8
- Total alkalinity
- 88 ppm
- Calcium hardness
- 273 ppm
- Cyanuric acid
- 36 ppm
Chlorine product set to liquid at 10%. Targets are the app's defaults, and you can move any of them.
WHAT TO ADD
| Parameter | Now → target | Product | Amount |
|---|---|---|---|
| Free chlorine | 3.0 ppm → 4.0 ppm | Liquid chlorine, 10% | 24.6 fl oz 3.1 cups · 727 mL |
| pH | 7.8 → 7.5 | Muriatic acid, 31.45% | 16.2 fl oz 2.0 cups · 480 mL |
| Total alkalinity | 88 ppm → 100 ppm | Baking soda | 3.23 lb 1.46 kg |
| Calcium hardness | 273 ppm → 300 ppm | Calcium chloride 77% | 6.22 lb 2.82 kg |
| Cyanuric acid | 36 ppm → 40 ppm | Stabiliser | 9.98 oz 283 g |
Each line carries its own note. Acid says to add half, wait thirty minutes and retest. Stabiliser says it takes three to seven days to dissolve and show up on a test. Cal-hypo says it will raise your calcium too.
These calculations are estimates for guidance only. Always verify chemical amounts with a second source before adding to your pool.
The numbers you keep looking up
These ranges are built into the app and shown against every reading you enter, so a value that has drifted is coloured before you have to think about it. They are here in full because most people want the chart, not the app, at two in the afternoon.
Ideal and acceptable water chemistry
| Parameter | Pool, ideal | Pool, acceptable | Hot tub, ideal |
|---|---|---|---|
| Free chlorine (FC) | 3 – 5 ppm | 1 – 10 ppm | 3 – 5 ppm |
| Combined chlorine (CC) | 0 – 0.5 ppm | 0 – 0.5 ppm | 0 – 0.5 ppm |
| pH | 7.4 – 7.6 | 7.2 – 7.8 | 7.4 – 7.6 |
| Total alkalinity (TA) | 80 – 120 ppm | 60 – 180 ppm | 80 – 120 ppm |
| Calcium hardness (CH) | 250 – 350 ppm | 200 – 400 ppm | 150 – 250 ppm |
| Cyanuric acid (CYA) | 30 – 50 ppm | 20 – 80 ppm | 30 – 50 ppm |
| Salt | 2700 – 3400 ppm | 2700 – 3400 ppm | 2700 – 3400 ppm |
Minimum free chlorine for your stabiliser level
| CYA (ppm) | Minimum FC |
|---|---|
| None or 0 | 1 ppm |
| Up to 20 | 2 ppm |
| 21 – 40 | 3 ppm |
| 41 – 50 | 4 ppm |
| 51 – 60 | 5 ppm |
| 61 – 70 | 6 ppm |
| 80 and over | 7 ppm |
Stabiliser protects chlorine from sunlight and also holds on to it. The more CYA in the water, the more free chlorine you need before the water is actually sanitised.
When you open the cover and it is green
Pick how bad it looks. The app sets the shock target from that, works the dose out for your volume, and walks the eight steps in order. This part is not behind the unlock.
Mild
Light green tint, you can still see the bottom.
Shock to 10 ppm
Moderate
Dark green, the bottom is barely visible.
Shock to 20 ppm
Severe
Opaque green or black, no bottom at all.
Shock to 30 ppm
- Test the water for FC, pH and CYA.
- Bring pH down to 7.2 first — chlorine works hardest there.
- Brush the walls, floor and steps to break up the colonies.
- Add the shock dose the app works out for your volume.
- Run the pump continuously. Do not switch it off.
- Backwash or clean the filter after 12 to 24 hours.
- Retest every 12 hours and top the chlorine back up.
- Stay out of the water until free chlorine falls below 5 ppm.
Screens
Scroll sideways, or focus the strip and use the arrow keys
The rest of it
- Volume from your dimensions
- Rectangular, round, oval, kidney, L-shaped or freeform, with a shallow and a deep end if the floor slopes. Get this right once and every dose after it is right.
- A log you can look back through
- Each test is saved with its date, a coloured dot per parameter, notes and a star for the ones worth remembering. Filter it, flag it, reopen any of it.
- Trend charts
- Seven, thirty or ninety days, with the average, low, high and direction for each parameter. Part of the unlock.
- Chemical reference
- Range tables, pre-worked dosing charts for common pool sizes, a compatibility list of what must never be mixed, and fixes for cloudy water, algae, pH drift and chlorine that vanishes.
- Backup and restore
- Export every pool and every test to a file, share it wherever you like, and import it back. Your record is not locked inside the app.
- Your units, your products
- Imperial or metric, Fahrenheit or Celsius, and a default chlorine type and bleach strength so the amounts come back in the product you actually buy.
What this app is careful about
Pool chemicals hurt people. ClearPool reduces the guesswork in the arithmetic. It does not remove the need to handle the product properly, and it is not a substitute for testing the water yourself.
- Never mix pool chemicals together, chlorine and acid least of all.
- Always add acid to water, never water to acid.
- Wear chemical-resistant gloves and goggles.
- Pre-dissolve granular chlorine in a bucket before it goes in the pool.
- Keep children and pets away during a shock treatment.
- Store everything cool, dry and out of the sun.
The same warning sits on the dosing screen inside the app, and the shock dose will not let you forget that nobody swims until free chlorine drops back under 5 ppm.
PRICING
$4.99one-time
The dosing calculator, the reference tables and the green pool guide work without paying anything. One payment adds unlimited pools and the trend charts, and removes the ads.
- More than one pool or hot tub
- Trend charts and statistics
- No ads
- Nothing renews
Questions
What does ClearPool cost?
It is free to use with ads, for one pool. A one-time $4.99 unlock adds unlimited pools and the trend charts, and removes the ads. Nothing renews.
Does it replace a test kit?
No. You still test the water yourself with a kit or strips and type the numbers in. ClearPool does the arithmetic that comes after the reading.
Does it work without internet?
Yes. Pools, readings and every calculation are stored and worked out on the phone. A connection is only used to serve ads before you unlock.
Does it do hot tubs as well as pools?
Yes. A hot tub uses its own ideal ranges — calcium hardness sits at 150 to 250 ppm instead of 250 to 350 — and the dosing scales to the smaller volume.
Which chlorine products does it handle?
Liquid chlorine at 6, 8.25, 10 or 12.5 percent, cal-hypo at 65 or 73 percent, dichlor and trichlor. It warns you when a stabilised product will push your CYA up.
Can I get my data out?
Yes. Settings has a backup that exports your pools and every water test to a file you can share or store, and an import to read it back.
Test it, type it, pour it
The next time the strip comes out of the water, you will know the amount before you reach the shed.