Green water isn’t bad luck.
It’s a missed number.
Never tested a pool before? Fought green water for years and still can’t keep it clear? AquaCheck turns your test strip into one exact answer — precisely how much to add, in the only order that works.
No install, no account — runs in any phone or desktop browser today.
Two problems every other pool app leaves you to solve yourself.
Add in the right order — enforced, not suggested.
Total alkalinity, then pH, then hardness, then chlorine, then stabiliser. Get that sequence wrong and you waste chemicals or damage your liner and heater. AquaCheck's wizard won't let you skip ahead.
“Other apps tell you how much to add. AquaCheck tells you what order.”
An exact total for your water — not a rate you do the maths on.
Most calculators hand you a rule of thumb: “about 30g per 10,000 litres.” AquaCheck asks your pool or hot tub's real shape and dimensions once, then hands back one number — exactly how much to add, today.
“Not a formula to work out. Just the number.”
Not case studies. Just people whose pools got easier.
“The app is sooo helpful and smart.”— a first-time pool owner, who'd never balanced a pool before AquaCheck. She used the water report and wizard on her phone and kept her pool clear and balanced for two weeks straight.
“If you are like me and you struggle with the chemical levels of your pool over the summer, you should check out this app. It has made my life a lot easier.”— a pool owner, commenting on the AquaCheck Facebook page
Every one of them makes the same three mistakes.
They lock you into one manufacturer, hand out generic advice, and let you add chemicals in whatever order you fancy — which is exactly how pools get ruined.
Four simple steps. No pool chemistry knowledge required.
If you can read a test strip, you can use AquaCheck — that's the whole idea.
Set up your water
Pick pool, hot tub, swim spa or cold plunge, then its exact shape and volume — metric or imperial.
Log today’s readings
pH, free chlorine, alkalinity, hardness and stabiliser — whatever your test kit gives you.
Get exact doses, in order
The wizard walks you through each chemical in the correct sequence, with timers between steps.
Watch the trend
History charts show whether you’re actually stabilising the water or just firefighting it.
Built around the way water actually behaves.
It won’t let you go out of order.
Total alkalinity, then pH, then hardness, then chlorine, then stabiliser — the sequence that actually protects your liner, heater and wallet. Each step comes with its own settling timer.
A trend, not just a snapshot.
Every reading is logged automatically. Line charts and plain-language summaries show whether your last dose actually worked, so you stop repeating the same fix every weekend.
One app, every body of water you own.
Pool, hot tub and a heated spa each carry their own target ranges — because they’re not the same water. Keep them all in one place, switch between them in a tap.
The safety-critical parts are free. Always.
Treatment order and timers are safety information — they stay free for everyone. Pro adds the exact numbers.
Free
- Full water report
- Treatment order wizard
- Step timers
- Unlimited water profiles
Pro
or £19.99 / year
- Exact gram / oz doses per chemical
- Full reading history
- Trend charts
- Everything in Free
Before you dose anything
Does AquaCheck lock me into one chemical brand?
No. It calculates doses in generic units (grams, ounces, litres) so you can buy whichever brand of chlorine, acid or alkalinity increaser is cheapest or already in your shed.
How is this different from a “grams per 10,000 litres” calculator?
Those give you a rate you still have to do the maths on yourself, and it's the same rate whether your pool holds 5,000 litres or 50,000. AquaCheck asks for your pool or hot tub's real shape and dimensions once, then every dose comes back as one exact number for your actual water — no working-out required.
Is it accurate enough to actually trust?
AquaCheck calculates doses from your exact volume and readings using standard pool chemistry formulas, and deliberately uses “approximately” language rather than claiming lab precision. It’s a calculator and a guide, not a substitute for your own test kit or professional advice on serious problems.
Do I need to create an account?
No. The free tier works entirely in your browser with no sign-up. Your profiles and readings stay on your device.
What water types does it cover?
Inground and above-ground pools, indoor and outdoor pools, hot tubs, swim spas, and cold plunges — each with its own target ranges, because a hot tub and a pool are not chemically the same water.
Is my data private?
AquaCheck has no backend in the free tier — there’s nothing to breach because there’s no server holding your readings. Anonymous, aggregate site analytics run on the website only, never inside the app.