Imagine you’re making a cup of tea. You drop in a sugar cube, it dissolves, and you can’t see it anymore. That’s a dissolved solid! In your pool, TDS includes everything from calcium and magnesium to sweat, pee (yes, we all know someone), and broken-down chemicals.
When you shock the pool or add tablets, those chemicals leave behind tiny particles. Over time, they build up like uninvited guests at a buffet who refuse to leave. The main culprit is water itself—every time you top off, you add more minerals, especially if you have hard water.
High TDS doesn’t make the water dangerous, but it makes it harder for chemicals to work. Your chlorine starts throwing a tantrum, and your pH swings like a playground pendulum.
How Do You Know If TDS Is High?
Your pool will start acting like a grumpy teenager: cloudy water, scaly buildup on the tiles, and a strange, flat taste if you accidentally swallow some (please don’t make a habit of that). Sanitizers become lazy, and algae might throw a pool party of their own.
You can’t see TDS with your eyeballs—it’s invisible, like your motivation to clean the gutters. That’s why you need a TDS meter, a cheap little gadget that looks like a thermometer from a sci-fi movie. Dip it in, and it gives you a number: anything under 1,500 ppm (parts per million) is fine, but over 2,500 ppm means it’s time to take action.
Saltwater pools are a special case—they start with a higher TDS from the salt itself. But don’t worry, they have their own little rules, like a VIP section at the pool club.
