Aquarium tools

The numbers you need before you buy fish, or after the water went cloudy. Each tool is one job. The formula is on the page. Nothing is uploaded.

If you are standing in the aisle with a list: stocking planner. New tank otherwise: volume, then filter, then heater, then substrate. Livestock last — after a cycle.

• Stocking plannerYou are asking how many fish fit — and whether they will live.
• Aquarium volumeYou have a tape measure and a box that claims to be 10 gallons.
• Fish compatibilityYou want to know if these fish can live together.
• Aquarium heaterThe kit heater is 50W and the tank sits on an exterior wall.
• Filter sizeYou are matching a hang-on-back or canister to tank gallons.
• Water changeIt is Sunday and you need the dose for 25%, not the whole tank.
• Tank dimensionsA listing is in cm, or you need to know if 60×30×36 cm is a 20 long.
• SubstrateYou are staring at 20-lb bags and a 2-inch target depth.
• Aquarium lightingYou want plants, not a 14-hour algae farm.
• CO₂The drop checker is green-ish and you want a number.
• FertilizerYou are mixing dry salts and do not want to guess the teaspoon.

Want a footprint turned into filter GPH, heater watts, and a 25% dose? Tank planner.