Want Your Koi's "Hi Plate" to Be Redder? First, Lower the NO3⁻ in the Water to Below 5 mg/L

Update time: 25-08-22 Views: 25

The "Hi plate" of koi is the core of their ornamental value—that bright red color, like a glow of morning, not only requires the blessing of innate genes but also relies on careful maintenance of water quality the day after tomorrow. Many fish keepers will find that the Hi plate of their koi will gradually darken, lose luster, and even have the problem of blurred color blocks. In fact, this is likely caused by a "hidden killer" in the water quality: excessive nitrate (NO3⁻) concentration. Want to make the Hi plate glow again? The first key step is to steadily control the NO3⁻ in the water below 5 mg/L.

5 Signs That the Hi Plate Is Darkening—Is Your Koi Affected?

The state of the Hi plate is a "barometer" of koi health and water quality. When NO3⁻ quietly exceeds the standard, these signals will give an early warning:

- Signal 1: The red color turns gray and dark

A healthy Hi plate should be like "rouge dotted", with bright color; if it turns into a dull "grayish red" and has no luster even under strong light, it may be that NO3⁻ has affected the metabolic function of the koi.

- Signal 2: Blurred edges of color blocks

The edges of a high-quality Hi plate should be as clear as "carved with a knife". If they gradually become blurred and blend with the white background, it may be that long-term high NO3⁻ causes disordered pigment deposition.

- Signal 3: Slow color development of new scales

When koi change scales, the red color of the newly grown scales should catch up quickly, but high NO3⁻ will inhibit pigment synthesis, causing the new scales to be "light pink" for a long time.

- Signal 4: The red color fades suddenly under stress

It is normal for the Hi plate to fade briefly after slight stimuli such as water changes and feeding, but if it cannot recover for a long time (more than 24 hours), it means that the water quality has put the koi in a "sub-healthy" state.

- Signal 5: Obvious differences among koi in the same pond

In the same fish pond, some koi's Hi plates are still bright, while others continue to darken—not due to genetic differences, but because high NO3⁻ has a more significant impact on koi with weaker constitutions.

Nitrate (NO3⁻): The "Hidden Killer" That Steals the Red Color Quietly

Why does NO3⁻ directly affect the Hi plate? The answer lies in the "pigment absorption chain" of koi.

The red color of the koi's Hi plate mainly comes from carotenoids (such as astaxanthin) in food. These pigments need to be absorbed through the intestines, transported through the blood, and finally deposited in the scales. When the concentration of NO3⁻ in the water exceeds 5 mg/L, two fatal problems will occur:

- Inhibiting carotenoid absorption: High NO3⁻ will damage the absorption function of the koi's intestines, making it impossible for the ingested carotenoids to be effectively converted into red pigments, and even more "color-enhancing feed" will be ineffective.

- Interfering with metabolic balance: NO3⁻ is the "end product of metabolism" of ammonia nitrogen (NH4⁺) and nitrite (NO2⁻). Long-term exceeding the standard will put the koi in a state of "chronic poisoning", reduce immunity, and naturally be unable to maintain the brightness of the Hi plate.

What's more tricky is that NO3⁻ is more "hidden" than ammonia nitrogen and nitrite—it will not cause koi to float like ammonia nitrogen, nor will it cause acute poisoning like nitrite, but long-term accumulation (exceeding 20 mg/L) will make the Hi plate problem continue to deteriorate, and even affect the lifespan of koi.

Controlling NO3⁻ Below 5 mg/L—AquaClean Helps You Build a "Full-Link Filtration System"

Reducing NO3⁻ is not simply "diluting with water change", but requires a set of filtration systems that can intercept from the source and decompose efficiently. AquaClean (AC) has been deeply engaged in aquarium filtration for 14 years. Aiming at the water quality characteristics of koi ponds, it has developed a series of filter materials, which work from the whole process of "physical interception - biochemical decomposition - water quality stabilization" to make NO3⁻ steadily "brake".

Step 1: Use "Biochemical King" to Decompose NO3⁻ Precursors and Cut Off the Source

Ammonia nitrogen (NH4⁺) and nitrite (NO2⁻) are the "raw materials" for generating NO3⁻. If they can be efficiently decomposed before they are converted into NO3⁻, the accumulation can be reduced from the source.

- Koi Biological Pillar: 1 pillar = 1 independent biochemical unit

This filter material with a patent (Patent No.: 2024204437079) has spiral vine cotton on the outer layer responsible for physically intercepting large particles of impurities, and high-density biochemical filter material on the inner layer provides a "luxurious residence" for nitrifying bacteria. Its unique "inner and outer structure" allows nitrifying bacteria to reproduce quickly, first converting ammonia nitrogen into nitrite, and then further decomposing it into low-concentration NO3⁻, which is efficient and stable throughout the process. It can be easily adapted to both the filter仓 of courtyard fish ponds and the filtration systems of large fish farms.

- Bio Foam Stone: 10 times the surface area, accelerating bacterial metabolism

The foam stone sintered at 900℃ has dense and connected pores inside, with a specific surface area more than 10 times that of traditional filter materials. This means it can "accommodate" more nitrifying bacteria, increasing the decomposition efficiency of ammonia nitrogen and nitrite by more than 30%. For large-space filtration scenarios such as koi ponds, its light weight and easy maintenance features can also reduce the cost of later management.

Step 2: Strengthen Physical Interception to Reduce "Pollutant Input"

Organic matter such as residual bait and feces in the water is the main source of ammonia nitrogen. If these "pollution sources" can be intercepted in advance, the "substrates" for NO3⁻ generation can be reduced.

- Koi Brush: Dual Effects of Interception and Bacteria Cultivation

This brush with a pentagonal star-shaped filament design has a rough surface and a large specific surface area. It can not only act as a "filter screen" to intercept suspended solids in the water (residual bait, fecal debris) but also provide attachment points for nitrifying bacteria. More importantly, it adopts innovative technology to slow down scale condensation, and is matched with a 316 stainless steel brush core, which is corrosion-resistant and durable. When cleaning, it can be cleaned with a high-pressure water gun, avoiding the problem of "hiding dirt and dirt" of traditional brushes.

- Filter Mat: Fine Filtration, Guarding the "First Line of Defense" of Water Quality

The spiral-structured vine filaments have a rough surface, and the adsorption area is 50% larger than that of traditional filter cotton, which can effectively block fine impurities; the 4cm high-density pore design can not only ensure smooth water flow but also allow nitrifying bacteria to quickly "form a membrane" on the surface. The natural and environmentally friendly material does not contain fluorescent agents and harmful glues, is safe and non-irritating to koi, and will not release pollutants even after long-term use.

Step 3: Stabilize the Water Quality Environment to Let Koi "Eat Well and Live Well"

After controlling NO3⁻ below 5 mg/L, a stable water quality is needed to allow koi to better absorb carotenoids. Two "auxiliary" filter materials from AquaClean can protect the color enhancement of the Hi plate:

- Mineral Brick: Supplement Trace Elements and Activate Metabolism

Rich in natural mineral elements such as Sr, Si, and Zn, it can be slowly released into the water, especially suitable for soft water areas in the south—these elements can enhance the intestinal absorption function of koi, increasing the conversion rate of carotenoids by more than 20%. At the same time, it can decompose organic matter in the water, adjust the pH value, and provide a stable environment for the nitrification system.

- Activated Oyster Shell: Stabilize pH and Hold the "Bottom Line" of Red Color

The activated oyster shell sintered at a low temperature of 400℃ can release minerals such as calcium and magnesium, and stabilize the pH at weakly alkaline (the most suitable pH for koi is 7.2-7.5) by adjusting the KH value of the water body. Stable pH can reduce koi stress and make the Hi plate pigment easier to deposit.

Good Water Raises "Red as Fire"—Starting with Controlling NO3⁻

The beauty of the koi's Hi plate has never been the result of a "single factor". When you feed high-quality color-enhancing feed to your koi, don't forget—only by controlling the NO3⁻ in the water below 5 mg/L can the "nutrients eaten" be truly converted into "visible brightness".

AquaClean has been deeply engaged in aquarium filtration for 14 years. From the filter materials specially used in the World Arowana Championship to the courtyard fish ponds of millions of fish keepers, it has always adhered to the concept of "only by doing filtration can we do filtration well". Whether it is the efficient decomposition of the koi biological pillar or the precise interception of the anti-scaling brush, each product is contributing to "low NO3⁻ water quality".