Calcium Sulfate Scale

Definition

A dense, hard scale driven mainly by calcium and sulfate concentration, with pH usually a secondary lever.

Calcium sulfate is far more soluble than calcium carbonate, so it often receives less attention at low cycles. Systems using sulfuric acid for pH control accumulate large sulfate loads, and high cycles can push water toward calcium sulfate saturation. Once formed, deposits are dense, hard, and resistant to normal acid cleaning, so prevention is far easier than removal.

Related concepts

Cycles of Concentration · Temperature Effect on Solubility · Concentration as Scale Driver

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Part of The Blueprint of Water · 🧪 chemistry