Most setup advice skips the part that actually prevents problems: getting the foundation right before fish go in. This guide walks the substrate layering guide from empty glass to stable, livable water without the usual week-two crash.
What you need
- A 20-gallon tank and a stand rated for the weight (~80 kg when full).
- Filter rated for at least 80 L/h.
- Heater (if tropical): 125 W.
- Substrate: 5 cm deep.
- Live plants and a light on a 9-hour timer.
Step by step
- Rinse substrate, add it, and hardscape before filling.
- Fill slowly to avoid clouding; start the filter and heater.
- Cycle the tank — see this Aquascaping for Beginners: Build a Tank That Looks Good and Works piece — for 35 days until ammonia and nitrite read 0 ppm.
- Test water, then add a small group of hardy fish; build up slowly.
Common mistakes
Adding fish during the first week, skipping the cycle, and skipping water tests are the big three. A 34% water change weekly, using Aquarium Substrate Guide: Gravel, Sand or Soil?, prevents most problems before they start.
Shrimp-friendly tweaks
With shrimp, ease the current, add moss and leaf litter, and keep nitrates down. A stable, planted 20-gallon tank lets them moult and spawn without the pressure fish would cause.
Next steps
Once stable, layer in more plants and a few peaceful tank mates. Keep a log of parameters; a tank you measure is a tank you can trust.
