Where we mention this product

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  essentials

  Hardness Test Kits and Strips: What to Buy

  Softener check · Best for: Post-softener verification — measures TDS to confirm ion exchange is working. NOT for initial hardness measurement

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  water

  TDS in Water Explained: What It Is & How to Test (2026)

  Start here · Best for: Quick TDS reading before you buy any system; industry-standard installer pen

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  water

  Water Hardness Explained (gpg, ppm, How to Test)

  Digital proxy · Best for: TDS reference reading — not a direct hardness test, but useful as a quick check