If you’ve ever stared at a “perfect” test strip while the pool still acts weird, you’re probably missing one of the quietest drivers in pool water chemistry: TDS. We dig into what Total Dissolved Solids actually means, why a simple digital meter belongs on every service truck, and how TDS can swing your saturation index enough to change your real-world results. Along the way, we unpack the old-school truth behind TDS, what the meter is really reading (conductivity), and why it is still a valu...