For koi keepers who take their pond seriously

Understand your pond.
Care for your koi.

Log water parameters in under a minute, see your pond health and stability scores instantly, and keep a complete record of your koi — readings, fish, health events, and treatments — in one calm, focused app.

Create an account Sign in →

Private preview · invite testers by sharing the sign-up link

pondlog.app/dashboard

Main pond

Showa Garden

+ Log reading

Pond health

Good

Stable · all core parameters in range

12koi

8days since change

14day streak

Water today

Temp

22.4°C

7.8

NH₃

0.00

NO₂

0.01

NO₃

Sound familiar?

Koi keeping is serious. Spreadsheets aren't.

Keeping water parameters in range is life-or-death for your fish. But most keepers track in notebooks, spreadsheets, or memory — scattered, hard to search, and giving you no sense of whether things are trending better or worse.

Searching back through a notebook to find your last pH reading

Manually calculating dosages for your pond volume at midnight

Not knowing if a KH reading of 4 dKH is actually fine or worth worrying about

Forgetting when you last changed water, or which fish showed spots three months ago

PondLog turns your test results into a clear, searchable history — and tells you what they mean.

What you get

Everything a serious keeper needs

Log in 60 seconds

Tap "Log reading", enter the values you tested, and save. Core parameters up front; advanced (ORP, GH, DO, TDS, salinity) unlocked on Keeper. Status dots show Ideal, Watch, or Act now — colour plus a word.

Pond health & stability scores

Every reading becomes a 0–100 health score with a plain-language read, plus a stability score that tracks pH swing, trends, and repeated warnings over time. Ammonia and nitrite pull the health score down hardest — so a high score means your water is safe right now.

Charts, Insights & compare

Single-parameter charts with ideal, watch, and danger bands on every plan. Keeper unlocks Insights — rule-based findings on trends, pH swing, correlations, and seasonal patterns — plus a compare explorer to overlay parameters and see Pearson correlation.

Pond setup & filtration

Record filtration components, pumps, and aeration. Turnover and aeration adequacy are calculated from what you enter — so your pond profile matches the system you actually run.

Koi collection records

A dedicated profile per koi — variety, size, attributes, acquisition, and a size log with growth chart. Bespoke variety plates give each fish a clear visual identity in the gallery.

Health, dosing & adjustments

Observations, diagnoses, and treatments from curated libraries, plus a health timeline and pond event log (water changes, maintenance, arrivals). Keeper adds a treatment dosage calculator and a KH/GH water adjustment calculator — deterministic maths for your pond volume.

The signature feature

One number. The whole picture.

The pond health score turns your latest test into a single 0–100 reading. A separate stability score tracks how steady your water has been over recent logs — pH swing, drifting KH, and repeated warnings.

Every score comes with a plain-language read. Tap a ring to open Insights and see what is driving the number.

Create an account

Pond health

Good

Stable · all core parameters in range

Atelier layer

Your collection, beautifully kept

Each koi gets a dedicated profile — variety, size, attributes, acquisition details, and a growth chart that builds from your size log. Bespoke variety plates give the gallery a clear visual identity (Kawarimono uses a text placeholder until its plate ships).

Crisp where you track the pond. Warm where you appreciate your koi.