Free Aquarium Maintenance Planner | Fish Tank Calculator

Generate a customized maintenance schedule for water changes, filter cleaning, and water testing based on your tank setup.

Successful aquariums are built on consistent maintenance, but the right cadence depends on tank size, stocking density, plant load, and whether CO2 and high lighting are in play. This calculator takes those inputs and returns a personalized maintenance schedule covering water change percentage, water change frequency, filter media cleaning interval, substrate vacuuming interval, and water-testing frequency. The goal is to replace vague rules of thumb with a tailored routine that matches your real bioload and equipment.

How It Works

Stocking level (light, moderate, heavy), planted versus fish-only, and CO2 presence are combined into a maintenance-intensity score. Higher scores compress intervals: heavily stocked, CO2-injected, high-light tanks may need 30-50% weekly changes with biweekly filter rinses and weekly testing, while a lightly stocked low-tech tank may only need 20% biweekly changes and monthly filter inspection. Substrate vacuuming is recommended less often in densely planted tanks where roots are disturbed.

Usage Scenarios

  • Setting a beginner-friendly schedule for a 75-liter community tank with eight tetras and two cories that fits a weekend morning routine.
  • Tightening intervals on a high-tech 120 cm aquascape with CO2, daily fertilization, and SAE-cleaned glass to keep nitrate under 20 ppm.
  • Building a low-maintenance Walstad-style planted bowl that may only need top-offs and occasional pruning rather than weekly changes.
  • Onboarding a vacation house-sitter with a simple printable checklist of daily checks, weekly tasks, and a once-a-month deep clean.

How to Use the Maintenance Planner

Enter your tank details to receive a customized maintenance schedule tailored to your specific setup.

Heavy stocking or heavy feeding may require more frequent water changes and cleaning than the suggested baseline.

This planner provides general guidelines. Always prioritize actual water test results and visual observation of your tank's health.

Frequently Asked Questions

How often should I do water changes?

Standard community tanks: 25–30% weekly. Heavily stocked or cichlid tanks: 30–50% weekly. Lightly stocked planted tanks with fast-growing plants: 25% every 2 weeks. Test nitrate weekly and adjust the schedule to keep it under 20–40 ppm.

When should I clean the filter?

Mechanical media (sponges, floss): rinse in tank water every 2–4 weeks when flow noticeably drops. Biological media (ceramic rings, bio-balls): rinse only when clogged, in tank water — never replace all at once or you crash the cycle.

How often should I test water?

New tanks (cycling): test ammonia, nitrite, nitrate, pH daily until cycled. Established tanks: nitrate weekly, full panel monthly. Test more often after fish additions, equipment changes, or unusual fish behavior.

Do I need to replace filter media?

Mechanical floss can be replaced when it falls apart (every 2–3 months). Sponges and ceramic media last years if rinsed gently. Activated carbon is exhausted after 4–6 weeks and should be replaced if you use it. Never replace all media at once.

Can I skip maintenance for a few weeks?

A mature, lightly stocked tank can usually go 2–3 weeks. Heavily stocked tanks need consistent weekly water changes — skipping leads to nitrate accumulation, pH drop, and stressed fish. If you travel often, stock conservatively or invest in an auto water-change system.