A concentrated source of bioavailable carbon, Krebs cycle intermediates, humic and amino acids, and naturally-occurring phytohormones.Brightwell Aquatics Florin-Fe Ferrous & Ferric Iron for Planted Fresh Water Aquaria,20 liter / 5.3 gal.* Provides both ferrous (Fe2+) and ferric (Fe3+) iron sources to maximize benefit to planted aquaria. * Two-tiered approach to iron supplementation consists of one ingredient to deliver immediate iron and another ingredient that slowly releases iron during the light cycle, when the aquarium is illuminated. * Over 50% stronger than most competing products. * Formulated utilizing extensive research on aquatic plant nutrient requirements.Product code: 3604Item No. PT-BA-FNF20L