Aquariums

Freshwater fishkeeping, planted tanks, and the gear that keeps them alive.

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If you're setting up your first freshwater tank, read this first. The mistakes that kill beginner tanks aren't subtle: too small, not cycled, wrong fish for the size. The site has tools that solve each piece if you go in the right order.

1. Pick a tank size, not a fish

Counter-intuitive, but right. Bigger tanks are more forgiving because water chemistry shifts more slowly. A 75 L tank is easier to keep than a 20 L tank. Use the tank volume calculator to convert dimensions if you're buying secondhand or building. Skip nano tanks (under 40 L) on a first build; they punish small mistakes.

2. Cycle the tank before adding fish

This is the step beginners skip. The nitrogen cycle takes 4-6 weeks: bacteria colonies need to grow before they can convert fish waste safely. Read the nitrogen cycle guide for what's happening and how to feed the cycle with ammonia (the fishless method). Don't trust "cycle in a week" products on the shelf.

3. Pick fish that fit the tank, not the other way around

Use the stocking calculator to pick a roster the tank can actually support. The catalog has 81 species with real schooling minimums, adult sizes, and compatibility data. Common mistakes: putting six fish that each "need" 75 L into a 75 L tank, or one fish that schools in groups of 10+.

4. Substrate and plants, if you want them

A planted tank is harder than a fish-only tank but more rewarding. Use the planted tank planner to pick plants that share substrate, light, and water-parameter needs. The aquarium substrate reference explains what each substrate does to pH and plant nutrition.

5. Heater, filter, lighting

The heater wattage calculator tells you what size heater the tank needs for the temperature delta. Aim for slightly oversized; an undersized heater runs continuously and burns out. The aquarium lighting calculator helps you match fixture PAR to plant needs.

6. Water changes and monitoring

Test water weekly for the first three months. Ammonia and nitrite should read zero once cycled; nitrate climbs and gets diluted by water changes. The water change calculator tells you how much to swap based on current nitrate.

If a parameter is off, don't dose chemicals to fix it; usually the right answer is a partial water change. Chemistry shortcuts often make things worse.