Potassium Sulphate provides potassium — one of the three primary macronutrients — without adding nitrogen or phosphorus. That makes it the cleanest way to maintain potassium levels independently, without throwing the balance of your other nutrients off.

Potassium is involved in enzyme activation, water regulation inside plant cells, and overall stress resistance. Plants that are short on potassium develop yellowing and browning at the leaf edges, become more susceptible to disease, and often look generally tired and unhealthy even when other nutrients appear adequate.

The sulphate form is specifically chosen over potassium chloride because it adds no chloride to the water. In an aquarium — particularly one with sensitive invertebrates — keeping chloride levels low matters. 250g is the standard amount for one full PPS-Pro macro mix.