Download it and start logging.
There is no registration, no email, no cloud account and no password to reset. AquaLog works the moment it opens — and keeps working if you never connect it to anything.
Aquarium water log · iOS
Your water, in eight numbers.
Log pH, ammonia, nitrite, nitrate, temperature, GH and KH in seconds. AquaLog keeps every reading, tells you what's due next, and shows where each parameter is heading — on your iPhone and iPad, with nothing sent to a server of ours.
Free to download · iPhone & iPad · no account required
No account
No ads, ever
Works offline
CSV export, free
Why AquaLog
What most aquarium apps get wrong.
We read the one-star reviews so you don't have to. These are the complaints that come up again and again across the App Store — and what AquaLog does instead, by design rather than by accident.
Not before you pay. Not after, either.
No banners, no interstitials, no advertising SDK collecting your device ID — and no “remove ads” upgrade to buy, because there is nothing to remove.
Local-first, with export that stays free.
Tanks, readings and photos are stored on your device. Export everything to CSV whenever you like, on every plan. Pro adds iCloud sync so a new iPhone or iPad picks up where you left off.
Unlimited water tests, even on Free.
Writing down your own measurements is the habit this app exists for, so we never meter it. Pro unlocks the insight — trends, charts, the symptom checker — not the ability to record.
The stocking estimate is a guide.
AquaLog estimates your load with the “1 inch per gallon” rule and shows the level — green, amber or red. It never refuses to add a fish. You know your tank better than a formula does.
Log 0 ppm and it stays 0.
Ammonia and nitrite at zero is the best news a test kit can give you. AquaLog records it as data — it doesn't quietly drop the value or treat it as an empty field.
The log
Eight parameters, one tap each.
A water test takes seconds to enter and stays useful for months. AquaLog keeps the numbers in a real grid so they line up, and reads them back to you in a sentence.
- pH, ammonia, nitrite, nitrate, temperature, GH and KH — the same row you'd write in a notebook, minus the smudged ink.
- Tabular figures in a 4 by 2 grid, so you can scan a tank's state in one look.
- One factual line under the grid: pH steady at 6.8, or nitrate down 4 ppm since the last test. No verdicts about your fishkeeping.
- Edit or delete any reading without losing the rest, and add notes — new fish, a water change, a treatment.
Latest reading
6.8
pH
0ppm
Ammonia
0ppm
Nitrite
21.5ppm
Nitrate
25.1°C
Temperature
7dGH
GH
5dKH
KH
Nitrate down 4 ppm since the last test
Log test
LogsUnlimited
Parameters8
Languages5
Accounts0
Features
Everything the log needs. Nothing it doesn't.
Logging is free and uncapped. Pro is for the things that turn a record into understanding — and it is priced as one purchase, not a habit tax.
Water test log
pH, ammonia, nitrite, nitrate, temperature, GH and KH — with the date, the time and a note. Unlimited on every plan.
Care reminders
Water changes, filter cleans, feeding, medication, tests. Daily, weekly, monthly or one-off, with native notifications. Pro removes the three-reminder cap.
Trends & charts
Each parameter over time, with its minimum and maximum marked. Drift shows up weeks before a fish tells you.
Photo album
A dated album per tank, grouped by month, with a cover photo for the list. Five photos free, unlimited with Pro.
Fish & stocking
Species, headcount and adult size, with a stocking level for the tank. Adding fish is always free — the estimate never blocks you.
Symptom checker
Pick what you're seeing — white spots, gasping, clamped fins — and read the likely causes and what to do next.
Cycle tracker
Follow a new tank through the nitrogen cycle: the ammonia spike, the nitrite spike, and the water change that ends it.
Your data, out
Every reading and note exported to CSV — free, on every plan, no upgrade prompt in the way. Your log belongs to you.
How it works
Three minutes to set up. Seconds a week after that.
Add your aquarium
Name, type, volume and roughly how many fish. AquaLog checks the stocking level as you type, then suggests a care routine you can agree with or change.
Rio Verde · planted · 120 L
Log a test
Enter the numbers from your test kit. Took the sample two days ago? Set the date. Nothing has changed? Copy the last test in one tap.
pH 6.8 · NH₃ 0 · NO₂ 0 · NO₃ 21.5 · 25.1 °C
See what's due
Home leads with this week's care, oldest first. Insights shows where each parameter is heading — so a slow climb is visible while it's still a small correction.
Feed fish · Daily — Water change · in 2 days
The app
Built like the app it is.
AquaLog is a native iOS app, not a website in a wrapper: system type, grouped cards that behave the way your other apps do, one accent colour, and a light and dark appearance that follows your device.
Native, not approximated
Real iOS controls and layout — the large titles, the segmented switches, the swipe actions, the bottom-sheet modals you already know.
One accent, spent carefully
A deep teal, plus small status dots for green, amber and red. No rainbow icon tiles, no gradients, no clutter competing with your readings.
Light and dark
Switch the theme on this page and the app above follows — it has the same two appearances, and matches your device by default.
Your aquarium off the page
Tanks without a photo of their own get the app's own drawn aquarium artwork, so the list never looks like a set of empty squares.
8
parameters
5
languages
0
accounts
0
ads
Privacy
Local-first, in plain words.
AquaLog is built so that the privacy policy can stay short. It collects nothing, needs no account, and has no server of its own to send your log to.
What is stored
Your aquariums, readings, photos, fish and reminders — on your device, in the app's own storage.
What is collected
Nothing. No analytics, no advertising identifiers, no account, no tracking.
What can leave the device
Only what you ask for: a CSV export you share yourself, or — with Pro — a sync of your log to your private iCloud. Purchases are handled by Apple.
Getting it out
The export is always free, and deleting the app removes its data. You are never locked out of your own log.
Pricing
Free to use. Pro for the insight.
Logging is free and unlimited, forever. Pro is one purchase for the analysis on top — a monthly subscription with a 3-day free trial, or a single lifetime payment.
AquaLog Free
$0forever
Everything you need to keep a single aquarium logged properly.
- Unlimited water tests
- One aquarium
- Three active reminders
- Five photos per aquarium
- Timeline, history and CSV export
- Trends and charts — Pro
- Symptom checker — Pro
AquaLog Pro
$3.99/ month after trial
Or $29.99 once — lifetime, no subscription, same features forever.
- Unlimited aquariums
- iCloud sync across your iPhone and iPad
- Parameter trends and charts
- Symptom checker
- Stocking calculator
- Unlimited reminders, photos and cycle tracking
- Everything in Free, unchanged
Prices shown in USD; the App Store charges in your local currency. Trials and subscriptions are managed in your Apple ID settings.
Questions
The things people ask first.
Do I need to create an account?
No. There is no signup, no email and no cloud account. AquaLog begins working the moment it opens, and it can go on working if you never connect it to anything at all.
Is logging really unlimited on the free plan?
Yes. Every plan logs unlimited water tests. We deliberately charge for the insight — trends, charts, the symptom checker — and never for writing down your own measurements, because logging is the habit the app exists to form.
What happens to my log if I lose my phone?
Your log lives on your device. Exporting to CSV is free on every plan, so you can always keep a copy somewhere else. With Pro, AquaLog also syncs to your own private iCloud, so a new iPhone or iPad picks up exactly where you left off.
Does it work offline?
Completely. Logging, reminders, photos and charts all work with no connection. Only iCloud sync and purchases need the network.
Is the stocking estimate a hard limit?
No. AquaLog estimates your load using the “1 inch per gallon” rule adapted to your tank's volume and type, then shows the level. If you disagree with it, you can still add the fish — it is a guide, not a gate.
Which languages does AquaLog speak?
English, French, Italian, Spanish and Portuguese (Brazil). The interface, reminders, symptom checker and onboarding are all translated — not just the menus.
Can I get my data out?
Yes. CSV export of your readings is free on every plan, including Free, and it exists so that your log is never held hostage by an app. Settings → Export data.
Is there an Android version?
Not yet. AquaLog ships for iPhone and iPad today. If the iOS version finds its aquarists, Android is the obvious next step — the app is built on a stack that crosses over.
Does it replace my water test kit?
No — and it never pretends to. You still test the water; AquaLog is where the results live, so that one reading becomes a history you can reason about. The symptom checker offers general guidance, not a diagnosis.
AquaLog for iOS
Keep every tank stable, one reading at a time.
Free to download, unlimited tests on the free plan, and a log that stays on your device unless you choose otherwise.