The H2O Labs Cleaning Crystals are a branded citric acid descaler formulated specifically for water distillers, dissolving stubborn limescale and mineral deposits from the stainless steel boiling chamber with no abrasive scrubbing required. While cheaper generic citric acid alternatives exist, using the branded H2O Labs crystals may protect your distiller warranty and ensure compatibility. Essential for anyone using a water distiller, particularly in hard water areas where scale builds up more rapidly.