Koi / goldfish pond: step-by-step setup

4 steps from choosing the spot to adding the first fish.

1. Size and depth

   Koi: 4,000 L+ and 1.2 m+ deep (they reach 60–90 cm). Part shade for temperature and algae.

2. Construction

   Sealed concrete or EPDM liner; bottom drain and surface skimmer; mechanical (vortex or drum) then biological filtration, UV, return pump and air.

3. Cycle the tank (the key step)

   Fill with dechlorinated water, run filter and heater, add an ammonia source (a pinch of food daily or 2 ppm ammonia) plus bottled bacteria. Test every two days: ammonia rises, then nitrite, then nitrate. Ready when ammonia and nitrite read zero three times in a row and nitrate shows (2–6 weeks). Log the tests and Zajel shows the stage.

4. Feeding by temperature

   Below 10 °C stop feeding; 10–15 °C light wheat-germ food; above 15 °C growth and colour food. Zajel follows the weather.