Seachem Flourish Iron Planted Aquarium Supplement 16.9 oz

For plants, iron is immobile, meaning they can’t divert the iron in older leaves to the newer ones. Plants use iron to produce chlorophyll, so a lack of iron results in a lack of chlorophyll, and thus yellowing of the younger leaves.
This ferrous iron gluconate supplement is highly concentrated (10,000 mg/L) and soluble in water at any pH level.
Plants easily benefit, without expending extra energy like they would need to with ferric iron.
Ferrous gluconate is better suited to foliar feeding than is iron-EDTA owing to the relatively weaker iron-gluconate bonding vs. iron-EDTA bonding.
Great source of carbon for plants.