The HM Digital TDS-3 is about the size of a thick pen or a very optimistic thermometer. You dip the tip into your water, press a button, and in about two seconds, you get a digital readout. It’s like a Magic 8-Ball, but instead of vague life advice, it tells you your aquarium is fine for your betta fish.
It also measures temperature—a surprisingly critical feature. Cold water holds more dissolved gas and can feel crisp; warm water often tastes flatter and reveals hidden flavors. The TDS-3 gives you both, which is like having a sensory upgrade for your tongue.
Bonus: it auto-locks the reading, so you don’t have to hold it in a cold glass of water while you fumble for your phone. That’s design thinking you can actually use.
