The Most Underrated Tool in Specialty Coffee? A TDS Pen.

Brewing a delicious cup of coffee isn’t just about selecting the right coffee beans, the right equipment, or having a basic understanding of how to use your grinder correctly. It’s also about how each element of your setup interacts with the coffee — especially your brew water.

If you’ve been brewing with mineral-enhanced water, you already know how much of a difference it makes. What used to be a niche topic only understood by scientists is now more accessible than ever — and tools like Apax Lab’s mineral blends have made it easy to take full control over your brew water.

At Nordic Brew Lab, we use Apax Lab’s mineral concentrates to enhance our brew water — or in some cases, custom-make the entire mineral composition from scratch to get full control. Either way, it's become easier and more convenient than ever before.

Apax Lab mineral blends: TONIK, JAMM, and LYLAC

Apax Lab offers three blends: TONIK, JAMM, and LYLAC. Each creates a unique mineral profile that’s ideal for great-tasting coffee. While there are endless ways to combine them, Apax Lab already provides a range of easy-to-follow water recipes online and in the included booklet. If you’re just getting into the topic of making your own water, we recommend starting with these recipes.

Want a deeper explanation of what TDS actually is and how it affects coffee? Check out our article on TDS and coffee brewing.

These recipes are excellent starting points — but if you're curious about taking it a step further and adjusting them to your own preferences, we highly recommend getting the TDS Pen.

Why a TDS Pen?

Most of Apax’s own water recipes land at a TDS (Total Dissolved Solids) between 90–120 ppm, which is ideal for filter coffee. But if you’re creating your own Apax recipes, or using a base water with unknown mineral content, a TDS pen is a must. It helps you make sure you’re not over- or underdoing your water with minerals.

Knowing the TDS of your water gives you precision, even if your base water isn’t fully demineralized. At Nordic Brew Lab, we typically start with 40 ppm water and then add our custom Apax recipes until the final water lands in the 90–120 ppm range. Without a TDS pen, it would’ve been difficult to get the right balance.

A simple tool that makes a big difference

If you’re into optimizing your own brew water — especially if you’re using Apax Lab mineral concentrates — you’ll benefit a lot from having a reliable TDS pen on hand. It’s a simple tool that gives you more control — making it easier to build, adjust, and repeat your water recipes with consistency.

See The Apax Lab TDS Pen in Our Store