Zero below 30°C to zero above 40°C: How one fish pond achieved 98% survival rate

The All-Climate Survival Program for Northern Koi Ponds: A Systematic Approach to Solving the Problem from Blistering Winter to Blasting Algae in the Heat of Summer‌

       In the extreme climate of the north, the design of koi ponds needs to break through the traditional thinking, not only to withstand the severe cold of -30℃, but also to resolve the algae crisis caused by the high temperature in summer. Based on the principles of fluid dynamics, thermodynamics and more than ten years of experience in breeding in high latitude areas, this paper constructs a set of solutions covering the whole cycle of design, construction, operation and maintenance.

‌Water body design and thermodynamic equilibrium‌
       Fish pool depth is the first line of defense for overwintering success. The depth of the main body of the pond must break through the lower limit of the permafrost layer, and it is recommended to dig deeper than 2.2 meters in the Northwest, and 2.5 meters in the extreme cold zone of the Northeast. This ultra-deep structure creates a stable water temperature layer, which can maintain the bottom water temperature at 4-5℃ in the safe zone of koi dormancy during the ice-off period. The bottom of the pond is designed with a curved surface in the shape of a pot, which together with the 30° gentle slope of the pond wall disperses the expansion pressure of the ice layer and avoids structural cracking. It is recommended to control the volume of the pool at 10-15 cubic meters, too large water heating costs increase dramatically, too small is the temperature fluctuation is violent. Pool within 1 meter of the perimeter of the need to lay 30cm thick ceramic layer, this porous material can not only block the surface of the cold conduction, in summer and can inhibit the growth of weeds.

‌Winter Survival Protection System‌
      When the cold front comes, the triple protection system is activated synchronously. The physical protection layer consists of 5cm thick XPS insulation board to construct a thermal barrier on the pool wall, together with the EPP foam board (density 35kg/m³) covering the water surface, which can reduce the heat loss by 60%. The dynamic temperature control system adopts titanium alloy heating rods (power configured according to 1W/liter) linked with the air-energy heat pump, which can stabilize the 10 tons of water body at 4℃ even in the environment of -30℃. Breathing hole management is the key to survival in winter: Reserve holes with a diameter of 30cm in the ice surface and install HIBLOW HP-100 air pump for continuous aeration, which can maintain dissolved oxygen >5mg/L and prevent the holes from freezing. In extreme cases, it is recommended to pre-build a propane heating system, which can be used to maintain the base temperature of a 10 m² area for 8 hours by burning 1 kg of propane during a power outage.

‌Summer Algae Prevention and Control Network‌
       The essence of algae outbreak in high temperature season is the uncontrolled triangle of nutrition, light and water temperature. Physical level adopts 70% shade rate of woven shade net, with floating plant floating island (water hyacinth accounted for ≤ 30%), can suppress the surface water temperature below the critical point of 28 ℃. The circulation system is equipped with a rotary drum microfilter (80 mesh screen) to achieve 20% of water filtration per hour, with K1 moving bed filter media (filling capacity 15%) to build an advantageous community of nitrifying bacteria. Biological prevention and control introduced killifish (3-5 per cubic meter) for algae nibbling, while EM bacteria (1:1000 concentration) were inoculated in advance in autumn to inhibit algae proliferation through microbial occupancy. Light management adopts 395nm wavelength UV blocking film, which can cut down the spectrum required by blue-green algae up to 85%.

‌Year-round dynamic regulation of water quality‌
        During the winter shutdown period, we focused on monitoring ammonia nitrogen concentration (need to be <0.2mg/L) and maintaining water quality through weekly water changes of 5%. Progressive feeding was initiated after the spring thaw, with embryo feed (281 TP3T protein content) fed when the water temperature exceeded 10°C, and water activity was assessed using a redox potentiostat (ORP values maintained at 250-300 mV). Phosphate concentration was tested daily during the high temperature period in summer (need to be <0.03 ppm) and treated monthly using phosphate adsorbents (e.g. Rowaphos). Add allicin during the fattening stage in the fall to strengthen the fish's immunity and ensure that the koi reach the golden ratio of length/weight (e.g., 50cm individuals need to be 3.2kg or more) before overwintering.

‌Practical tips for controllable costs‌
       Ground source heat pump system exchanges heat through 3m deep buried pipes, which can save 40% energy compared with conventional heating. photovoltaic drive system supplies power for UV germicidal lamps in summer, and 6㎡ photovoltaic panels can satisfy the demand of 10 tons of water body. The ecological floating island transformed from old tires is filled with ceramic granules and planted with foxtail algae, costing only 1/5 of commercial products. covering the water surface with a car windshield sunshade during the overwintering period, its multi-layer heat preservation structure delays the formation of the ice layer by 15 days.

‌Risk early warning and emergency response mechanisms‌
       Mechanical de-icing needs to be activated when the ice thickness exceeds 25cm (using a steam ice melter rather than hammering). On the eve of a rainstorm, 100 mesh emergency filter bags should be added to the filter bin to prevent suspended matter from impacting the biochemical system. When koi are found to be flopping sideways or floating, immediately use sodium percarbonate (20g per ton of water) for emergency oxygenation. It is recommended to always have a water quality first aid kit: including calcium and magnesium ion regulators, VC stress relievers, methylene blue and other core pharmaceuticals.

Structural construction (7-10 days)‌

‌1. Earthmoving‌

• Main pool: 2.2 meters deep (including 0.3 meters of anti-freeze buffer layer), slope ≤ 30°
• Shallow water: 0.8 meters deep, the area of 30%, the edge of the non-slip grooves
• practical skill: Pre-embedded PVC conduit pipe (Φ110mm) at the bottom of the pool to the catchment pit, to cope with the accumulation of water in rainstorms.

‌2. Foundation strengthening‌

• Pouring of pool wallC30 reinforced concrete(thickness 20 cm, reinforcing grid 15 x 15 cm)
• Pool Bottom LayingXPS insulation board(5cm thick, compressive strength ≥300kPa)

‌3. Waterproofing‌

• Double waterproofing:
  ① Substrate: 1.5mm thick HDPE geomembrane (welded seams, inflatable detection)
  ② surface layer: cementitious osmosis crystallization waterproof coating (painted 2 times)
• Cost optimization: Partial replacement of concrete with a three-component soil (lime:clay:sand = 1:2:4) in rural areas

       This set of solutions in Heilongjiang Mohe, Xinjiang Altay and other extremely cold areas after field verification, to achieve the overwintering survival rate of 98% or more, summer algae control compliance rate of 95% hard indicators. The core lies in breaking the seasonal limitations and building a water body self-balancing system - locking the survival temperature in winter through thermodynamic design, and curbing algae outbreaks in summer with the help of ecological competition. Breeders need to establish a three-tier filing system of daily water temperature records (Mijia Bluetooth thermometer is recommended), monthly water quality tests (HANNA HI97104 portable photometer), and annual pool checkups and repairs (with a focus on the HDPE membrane seams), to ultimately cultivate robust and colorful northern koi in a harsh climate. For more information, please contact us at 020-82686289.