Jezírka na klíč / Koi pond and filtration
A koi pond is built for fish, not plants. Depth, a bottom shape that does not trap silt, and filtration sized for the stock are decisive. We will design and build a pond in which koi can thrive and the water remains clear.
I would like a pond design
Koi carp are large fish with high feed consumption and consequently high waste production. A plant zone would not sustain them, and the fish would also disturb it. Therefore, we build koi ponds as smooth tanks at least 1.5 metres deep, preferably 2 metres, with steep walls, a floor sloping towards bottom drains, and without gravel where sludge could accumulate. The liner is usually black or dark green to make the fish colours stand out.
Plants for koi ponds should be placed only in separate shallow areas or on floating islands where fish cannot reach them; their main function is to shade the water surface.
We design filtration based on water volume, the number and size of fish, and feeding intensity. The rule is to circulate the entire volume approximately once per hour. The sequence is as follows:
Undersized filtration is the most common reason a koi pond fails to function. A filter „for 20 m3" from a box assumes a few small fish, not ten koi measuring 50 cm each. That is why we ask about the stock before we start drawing plans.
Koi overwinter at the bottom in depths exceeding 1.5 metres, where the water temperature remains stable around 4 degrees. During winter, filtration is either kept running on a reduced setting or switched off while aeration maintains an opening in the ice. In spring, once the water warms above 10 degrees, the filter is restarted and feeding of the fish begins. We can assist with seasonal adjustments or take them over as part of maintenance.
Do you have a pond with fish and green water? Filtration can also be added later: a gravity system with a drum filter requires a shaft next to the pond, while a pumped pressure filter with UV can be hidden in a corner without excavation. We will assess the volume, stock and access and propose a solution that makes sense.
At least 1.5 metres, preferably 2 metres. Depth protects fish from predators, maintains stable temperature and allows safe overwintering. Shallow koi ponds overheat in summer and freeze solid in winter.
As a rough guide, approximately 1 m3 of water is required for one adult koi with good filtration. Therefore, a pond of 20 m3 should hold around 10 to 15 fish rather than 40. The fish grow to 60 to 80 cm, and this must be taken into account from the start.
The UV lamp eliminates floating algae that turn the water green. It does not address filamentous algae on the walls or water quality, but for koi ponds where clarity is desired, it is a standard part of the filtration system.
The depth and steep walls prevent herons from entering the water, while fish learn to hide near the bottom. Additionally, a taut wire around the bank or a net in winter, when fish are sluggish, provides supplementary protection.
Just a few details. We will contact you within 24 hours to discuss your expectations for the water feature and arrange a free survey.