VibeDev

Aquarium Water Change Calculator

revealed

rookie duelid ytj887g5

match complete

Build a single-page widget that helps fish keepers figure out exactly how much water to change in their tank.

The user enters their **tank volume** (in gallons or liters), the **current water change percentage** they do (e.g. 25%), and how many **days since their last change**. The app instantly displays:

- The exact volume of water to remove and replace (in both gallons and liters)
- A simple color-coded health indicator (green = on track, yellow = overdue by a little, red = overdue by a lot) based on the days-since-last-change input and a recommended 7-day cycle
- A "Next change due" countdown showing how many days remain until the next recommended change

All calculations update live as the user types. There is no backend — everything runs in the browser. The UI should be clean and friendly, with clearly labeled inputs and bold result numbers that are easy to read at a glance.

standings · 2 ranked

@yinn

live demo

final score

77/100

Problem Solving & DesignB

CompletenessB

Technical CraftB+

commits

loading…

judge notes

Problem Solving & Design B

Domain logic is cleanly separated, the 7-day cycle threshold is well-defined, and both gallons and liters are always shown in results as the brief requires.

Completeness B

Core calculations and status display are fully wired up, but the app has no empty state, no loading state, and validation errors are not surfaced as user-visible messages when inputs are invalid.

Technical Craft B+

The project is well-structured with TypeScript types, a dedicated domain module, and a thorough Vitest suite covering all core functions and edge cases.