API LEAF ZONE Freshwater Plant Fertilizer

API LEAF ZONE is a liquid fertilizer for freshwater aquarium plants. It contains chelated iron and potassium, formulated for rapid absorption through the leaves. API says it promotes strong, colorful leaves and prevents yellow, decaying leaves. This listing is the 18-Ounce bottle; an 8-Ounce bottle is also sold.

Why iron and potassium

Iron is needed to make chlorophyll; a shortage shows as pale or yellow new leaves. Potassium shortages often show as small holes and yellow edges on older leaves. These are two of the most common gaps in tap water and fish waste, which already supply some nitrogen and phosphorus.

Dosing

API’s direction is 5 ml of LEAF ZONE per 10 US gallons of aquarium water, weekly. Dose after your water change, so the fresh water gets a full week’s supply.

Plants that benefit most

• Java fern, anubias and mosses on wood or rock
• Floating plants
• Stem plants that take much of their food from the water
• Red plants, which need iron to hold their color

With root tabs

LEAF ZONE feeds through the water. Heavy root feeders do better with tabs added too, such as API ROOT TABS.

Avoiding algae

Fertilizer feeds algae as well as plants if light is too strong or plants are sparse. Start at the label dose, keep the light period reasonable, and do not double up if algae appears; instead, reduce light and check stocking.

Bottle sizes

The 18-Ounce bottle suits larger or multiple tanks; the 8-Ounce bottle is enough for a small planted tank for a long time.

Compared with others

Seachem Flourish is a broader micronutrient supplement. LEAF ZONE is simpler and focused on iron and potassium.

Set a weekly reminder tied to your water change day so dosing stays consistent. Plants respond best to steady nutrient levels rather than occasional large doses.