Aquarium Stability Planner

What changed in your tank before the problem showed up? Aquarium Stability Planner is a logbook for your freshwater, reef, or planted tank that helps you answer that question from your own records. Log water tests, maintenance, dosing, equipment, and livestock — and when something looks off, look back at everything that happened in the days before, in order. Your records stay on your phone. No account, no ads, no tracking what you do. ▶ TRACK YOUR TANK • Tank types: freshwater, reef, planted, brackish, fish-only marine, or custom. • Parameters matched to your tank type: ammonia, nitrite, nitrate, pH, GH, KH, temperature, alkalinity, calcium, magnesium, salinity, phosphate, CO₂, and photoperiod. Add your own parameters with a name and unit. • Unlimited readings and a chart for each parameter. The shaded band is a visual reference only, not a pass/fail alarm. • One unified timeline: water changes, filter cleanings, dosing changes, equipment, livestock additions and losses, and observations. • Livestock (fish, corals, inverts, plants) and equipment log. • Maintenance reminders with notifications on your phone. ▶ STABILITY INVESTIGATION (PRO) Report a problem — algae, coral stress, cloudy water, odd fish behavior, fish loss, plant decline, or odor — and the app rebuilds the previous 7, 14, or 30 days: • A reconstructed timeline of tests, maintenance, dosing, equipment, and livestock. • "What changed beforehand?": fast changes and values that are unusual for YOUR tank, measured against its own history instead of a generic range. • Straight talk about data quality: parameters that weren't tested, sparse testing, too little history, several changes at once, or a tank that may still be cycling. An investigation shows the order of events, not a cause. It doesn't diagnose or hand out confidence percentages, and when the data isn't enough, it says so: "insufficient information." You decide what to check next, with an honest picture of your records. ▶ CALCULATORS • Water change: liters to remove and replace for your tank volume and target percentage. • Reef dosing (alkalinity, calcium, magnesium): splits the adjustment over several days when it exceeds a safe daily maximum. Available for reef, marine, and custom tanks. • Unit conversion: °F ↔ °C and salinity SG ↔ ppt (approximation). • Cycling estimator: guidance based on your ammonia and nitrite readings, never a confirmation. ▶ FREE VS. PRO Free, with no time limit: • 1 aquarium • Unlimited readings, charts, and timeline • Reminders and calculators • Livestock and equipment log Pro, one-time purchase (no subscription): • Stability investigations • Unlimited aquariums • Historical reports • Full backup: export your data and restore it on another phone ▶ PRIVACY Your records live only on your device: no account, no cloud sync. Works offline; you only need a connection to buy or restore Pro. Purchases are processed by Google Play. In English and Spanish, with light and dark themes and an animated water interface — waves, bubbles, and a swimming fish. Aquarium Stability Planner is a record-keeping tool. It doesn't replace advice from an experienced aquarist.