Just as your fish need to have a healthy diet and clean water to grow big and beautiful, plants also require a special “diet” of lighting and nutrients to thrive. To have the proper building blocks needed to grow well, they need large amounts of macronutrients (like nitrogen, potassium, and phosphorus) and trace amounts of micronutrients (like magnesium and zinc). Our Easy Green all-in-one liquid fertilizer contains all the correct ratios of these macronutrients and micronutrients that can be easily dosed with a simple pump head or dropper cap. It comes with a very strong 9.21% concentration of potassium (also known as soluble potash or K2O), so when is it necessary to dose even more potassium in your planted tank?

Do My Aquarium Plants Need More Potassium?

Potassium is responsible for all sorts of vital functions in live plants, both terrestrial and aquatic species. It regulates water and nutrient movement between plant cells, is used in photosynthesis and protein synthesis, activates dozens of enzymes, and controls the stomata (or pores on the leaf’s surface that open and close to allow gas and water exchange). Potassium also transports sugars, starches, and other organic compounds so they can be stored inside bulbs, tubers, and fruits.

Do my aquarium plants have a potassium deficiency?

Most of the time when a plant is lacking macronutrients (like potassium), any remaining macronutrients within the plant are moved from the older leaves to the newest shoots to save them. It is very easy to see when you have a potassium deficiency because the older, existing leaves develop very distinctive pinholes that are sometimes rimmed with brown or yellow. If the potassium deficiency continues, then the pinholes will grow into bigger and bigger holes until the entire leaf decays away. For more details on plant nutrient deficiencies, see our full article.

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Plants that lack potassium develop small pinholes on the older leaves.

In the majority of planted tank, Easy Green fertilizer provides plenty of potassium and other nutrients, so you won’t need to add any supplemental fertilizers. However, if you are growing high light plants in a high tech aquarium with carbon dioxide (CO2) injection, they can grow incredibly quickly and may be absorbing potassium at a much faster rate than other nutrients. Also, some plants like java fern and anubias thrive in environments with more potassium. Therefore, if your tank has greater potassium demands than usual, keep reading.

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Some plants like java fern and anubias can consume greater amounts of potassium and may develop yellowing and browning if they lack the proper nutrients.

How Often Should I add Potassium to My Aquarium?

Easy Potassium is our potassium supplement that contains a 9.12% concentration of soluble potash (K2O) derived from potassium sulfate and potassium citrate. Like all the products in our Easy Fertilizer line, it is completely safe for fish, shrimp, snails, and other aquatic animals. Plus, it comes in two sizes with easy-to-use dispensers for quick dosing.

If you aren’t sure how much potassium your planted tank needs, start off slowly and only dose once a week. Wait two weeks to see the effect it has on your plants, and consider increasing the dosage to two to three times a week if needed. Several planted aquarium articles recommend aiming for approximately 5–20 ppm potassium in your water, depending on the needs of the plants. In general, an excess of potassium in planted tanks does not cause algae growth, and experienced aquatic horticulturists have dosed up to 100 ppm potassium in high tech planted aquariums without experiencing any toxicity issues.

Easy Potassium

Why doesn’t Easy Green contain more potassium? As mentioned before, Easy Green already contains very high amounts of potassium. In fact, our formula has already reached the saturation point for potassium, so the only way to add more is to create a separate potassium supplement. For most aquariums, the amount of potassium in Easy Green is plenty sufficient, but if you have a unique case of using a high tech aquarium or owning lots of potassium-hungry plants, make sure to give Easy Potassium a try.