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.
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.
- The 500 ml (16.9 oz) bottle treats 5,000 gallons total and has a pump head on top. Dose 1 pump (1 ml) per 10 gallons of water to add 2 ppm of potassium.
- The 120 ml (4 oz) bottle treats 1,200 gallons total and has a dropper cap on top. Dose 2 drops per 1 gallon of water to add 2 ppm of potassium.
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.