Root tabs

Root tabs are small fertilizer tablets, usually a compressed capsule of nutrients, that get pushed a couple of inches into the substrate near the base of root-feeding plants. Unlike liquid fertilizer, which dissolves into the water column for plants that feed mainly through their leaves, root tabs deliver nutrients directly to the root zone where heavier feeders like swords and crypts take them up.

They are especially useful in tanks with an inert substrate such as plain gravel or sand, which holds no nutrients of its own, but they are also used alongside aqua soil once its built-in nutrients start to run low after a year or so. Most root tabs are formulated to release nutrients slowly over weeks, which reduces the risk of a sudden nutrient spike compared to overdosing liquid fertilizer, and they are typically replaced every one to three months depending on the brand and how heavily planted the tank is.

When placing root tabs, push them in near but not directly touching the roots of the target plant, since placing one too close can burn delicate root tissue. A common mistake is using root tabs as a substitute for a full fertilizing routine in a tank full of stem and floating plants, which feed mainly from the water column and get little benefit from nutrients buried in the substrate.