Bluelab pH 4 Buffer Solution | Calibration Solution for pH Meters & Pens | 250ml & 500ml

🌱 Calibrate with Confidence — Get Your pH Readings Right Every Time

Accurate pH readings start with proper calibration. The Bluelab pH 4 Buffer Solution is the essential slope reference used in every two-point calibration — working alongside pH 7.0 to make sure your Bluelab pH meter or pen is reading exactly where it should be. No guesswork. No drift. Just happy, healthy plants.

📦 Available Sizes

• 250ml — Great for home growers doing regular monthly calibrations
• 500ml — Perfect for larger setups, commercial grows, or high-frequency use

✅ Why Growers Choose This

• 🎯 Two-point calibration essential — pH 4.0 is the slope reference that pairs with pH 7.0 for precise results
• 🔬 NIST-certified — referenced to internationally traceable laboratory standards
• 💧 Made specifically for Bluelab products — no compatibility concerns, just reliable performance
• 📅 Calibrate monthly — or whenever your meter prompts you, to keep readings accurate
• ⚡ Start measuring immediately after calibration is complete
• 🌿 A must-have in every grower's toolbox — alongside conductivity and pH 7.0 solutions

🔧 How to Use

Clean your pH probe first, then calibrate in two steps: set to pH 7.0 (buffer), then to pH 4.0 (slope). The process is the same for all Bluelab pH meters and pens — quick, simple, and consistent. Once done, you're ready to measure straight away.

💡 Tips to Keep Your Solution Fresh

• Always decant into a small cup before use — never dip directly into the bottle
• Discard used solution — don't pour it back in
• Store in a cool, dark place with the lid tightly sealed
• Keep out of reach of children

📐 Size Comparison

🌿 Don't let inaccurate readings hold your grow back. Add the Bluelab pH 4 Buffer Solution to your cart and calibrate with confidence today.