Planted and Nano Tanks: Small Green Worlds

Nano or Bigger?

OATA, the UK ornamental fish trade body, describes nano tanks as starting at about 2.6 gallons (10 liters). They look lovely on a desk, but small volumes of water change temperature and chemistry quickly, so mistakes show up fast. As OATA puts it, larger tanks are more stable and less prone to swings, which also helps keep algae down.

If you are new to fishkeeping, a tank of around 15 to 20 gallons (57 to 76 liters) is more forgiving. If you choose a nano, stock it very lightly.

These follow OATA's minimum tank sizes for each group. See bettas, rasboras and shrimp.

Planting Step by Step

1. Position the tank on a level stand that takes the full weight, out of direct sun and away from heaters and drafts.
2. Add a plant substrate (aqua soil or a gravel made for plants), banked higher at the back. Ask whether yours needs rinsing.
3. Place the hardscape: wood and stone first, moved around until you like it.
4. Add about 2 inches (5 cm) of water, then plant: short plants at the front, tall ones at the back, using tweezers. Remove any rock wool from the roots.
5. Attach epiphytes such as anubias, bucephalandra and mosses to wood or stone with thread or plant glue; don't bury them.
6. Plant heavily from the start; OATA notes this helps stop algae getting ahead of your plants.
7. Fill gently, pouring onto a plate or into a colander, and add water conditioner. Then fit the filter, heater and light.

Light, CO2 and Fertilizer

• Light: OATA suggests a timer giving at least 6 to 8 hours a day, up to 10 to 12 hours if the light ramps up and down, which dimmable LEDs do easily. Start shorter and increase slowly; too much light too soon feeds algae.
• CO2: extra carbon dioxide speeds up plant growth, but OATA notes it isn't essential, and many low-tech tanks grow well without it. If you use it, follow the instructions and dose carefully: too much can harm fish and swing pH.
• Fertilizer: a root tab for heavy root feeders and a liquid fertilizer at the dose on the label. More isn't better.

Easy low-tech plants include anubias, java fern, cryptocorynes, mosses and floating plants.

Cycling and Stocking

Plants use some fish waste, but OATA is clear that a planted tank still needs a filter and water changes. Let the tank settle for a day or two, then cycle the filter until ammonia and nitrite stay at zero; see cycling a tank. Some new plant soils release ammonia or cloud the water at first, so test before adding livestock.

Add fish or shrimp slowly, a few at a time. Shrimp are very sensitive to copper, so check fertilizers and any products before use.

Keeping It Tidy

• Change part of the water every week and test regularly.
• Trim plants before they block light to the lower leaves, and remove dying leaves.
• Rinse filter sponges in old tank water, never under the tap.
• If algae appears, cut the light hours back and check your fertilizer and feeding; see cloudy water fixes.

For fish treatments or medicines: see your vet or a pet supply store with trained staff. Many treatments harm shrimp and some plants, so ask before adding anything to a planted tank.