Parametra Aqua

(Acidity and Alkalinity): The homeostasis of life. Koi prefer slightly alkaline water (pH 7.0-8.5). Severe fluctuations can cause stress in fish, damage their mucus, and even lead to the collapse of the nitrification system. 

Ideal level for Fish Pond =  7.5 – 8.0 

Increase level = use baking soda

decrease level = partial water change or put some driftwood in the water

Ideal level for swimming pools =   7.4 – 7.6 

(Residual Chlorine): The survival threshold. Chlorine in tap water is highly toxic to the gills of koi fish; monitoring ensures safe hydration and prevents toxic death. 

Ideal level for Fish Pond =  0.00 ppm (mg/L) — anything above this is harmful

When going over this level =  Use a commercial anti-chlorine / dechlorinator  

Ideal level for residential pool =  1.0 – 3.0 ppm 

Ideal level for commercial / public pools =  2.0 – 5.0 ppm 

Ideal level for spa / hot tubs =  3.0 – 5.0 ppm 

(Oxidation-Reduction Potential): Water quality cleanliness. The higher the value, the stronger the self-purification ability of the water body and the faster the decomposition of organic waste (fecal residue), making it a key indicator of the transition from "fresh water" to "old water."

Ideal level for Fish Pond =  250 – 350 mV 

Ideal level for swimming pools =  650 – 750 mV 

(salt content): Osmotic pressure and disease prevention. When koi are transferred to a new pond or are sick, the salt concentration needs to be adjusted (usually 0.3%-0.5%) to regulate osmotic pressure and kill some parasites; precise monitoring can prevent the concentration from becoming too high. 

Ideal level for Fish Pond =  0.00 – 0.10% (0 – 1,000 ppm) 

(Electrical Conductivity): Mineral content. Reflects the total ion concentration of the water body. Sudden changes in values usually indicate the entry of external contaminants or excessive evaporation of water, leading to overly concentrated water quality. 

Ideal level for Fish Pond =  100 – 300 µS/cm 

Ideal level for swimming pools =  

• 1,500 – 3,000 µS/cm → standard pools 
• 3,000 – 6,000 µS/cm → saltwater pools

(Total Dissolved Solids): Old water alert. High values indicate that too many metabolic waste products and impurities have accumulated in the water, which is a clear signal that "it's time to change the water." 

Ideal level for Fish Pond =  100 – 300 ppm  

Ideal level for swimming pools =  

• 500 – 1,500 ppm → standard pools 
• 2,500 – 4,500 ppm → saltwater pools

(Temperature): The metabolic engine. Koi fish adjust their body temperature with changes in water temperature. The temperature directly determines your feeding frequency, oxygen consumption, and the activity level of the fish's immune system. 

For fish ponds =  Optimal range: 18°C to 24°C 

For Koi ponds =  Stress starts to appear:

• Below 10°C → metabolism slows a lot, feeding stops 
• Above 28°C → oxygen drops, stress increases

Ideal level for swimming pools =   26–29°C (comfort range for humans)