--- product_id: 32105900 title: "pH 4.0 & 7.0 Calibration Solution Kit - pH Meter & pH Pen Calibration for Balanced Nutrient Solution NIST Traceable | Hydroponics, Gardening & Growing Tents (500 ml/ 16.9 Fl Oz Each)" brand: "bluelab" price: "£44.69" currency: GBP in_stock: true reviews_count: 8 category: "Bluelab" url: https://www.desertcart.co.uk/products/32105900-ph-4-0-and-7-0-calibration-solution-kit-ph store_origin: GB region: United Kingdom --- # Long shelf life, ready-to-use Dual pH 4.0 & 7.0 calibration NIST traceable precision pH 4.0 & 7.0 Calibration Solution Kit - pH Meter & pH Pen Calibration for Balanced Nutrient Solution NIST Traceable | Hydroponics, Gardening & Growing Tents (500 ml/ 16.9 Fl Oz Each) **Brand:** bluelab **Price:** £44.69 **Availability:** ✅ In Stock ## Summary > 📊 Calibrate like a pro, grow like a boss! ## Quick Answers - **What is this?** pH 4.0 & 7.0 Calibration Solution Kit - pH Meter & pH Pen Calibration for Balanced Nutrient Solution NIST Traceable | Hydroponics, Gardening & Growing Tents (500 ml/ 16.9 Fl Oz Each) by bluelab - **How much does it cost?** £44.69 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.co.uk](https://www.desertcart.co.uk/products/32105900-ph-4-0-and-7-0-calibration-solution-kit-ph) ## Best For - bluelab enthusiasts ## Why This Product - Trusted bluelab brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Effortless & Ready:** Pre-mixed, ready-to-use bottles save time and eliminate guesswork. - • **Versatile Application:** Perfect for hydroponics, gardening, aquariums, and swimming pools. - • **Dual Calibration Power:** Includes both pH 4.0 and 7.0 solutions to cover a wide calibration range. - • **Precision You Can Trust:** NIST traceable solutions ensure lab-grade accuracy for your pH meters. - • **Extend Your Meter’s Life:** Regular calibration maintains peak performance and longevity of your pH pen. ## Overview This Bluelab pH Calibration Solution Kit includes two 500ml bottles of pH 4.0 and 7.0 solutions that are NIST traceable, ensuring precise and reliable calibration for pH pens and meters. Designed for hydroponics, gardening, aquariums, and pools, it extends device longevity with easy, ready-to-use formulas that maintain accuracy and save you time. ## Description Product description Review: Perfect - I followed the directions to the letter and the calibration solutions worked perfectly. I feel so much better about my grow knowing the reading I am getting are true readings. The solution hand my Blue Labs OnePen with perfectly calibrated and fast results Review: Good - Good ## Features - Ensures accurate readings - Our pH calibration solution helps maintain the accuracy and reliability of a pH pen, probe, or tester. Calibration ensures accurate readings. This helps keep the pH level in check for the health of plants, swimmers, or aquatic life. - NIST Traceable - Our pH calibration solutions are NIST traceable and meet the highest quality standards. This set includes two crucial pH levels, pH 4 and pH 7, allowing you to calibrate a wide range of pH instruments. - Improves the longevity of the pH pen or tester - Regular calibration helps extend the life of your pH meters by maintaining their performance. Useful for providing accurate pH in hydroponics, aquariums, swimming pools, or gardens. - Easy-to-use and long shelf life - Our electrolyte solutions are ready-to-use right out of the bottle, saving you time and effort. Our pH calibration solutions don't need frequent replacements as they have a long shelf life. - How to calibrate - Make sure your pH pen or probe is clean and hydrated. Turn it on. Place the probe tip in a fresh pH 7.0 calibration solution. Rinse the pen or probe tip in clean tap water and shake off the excess. Calibrate to pH 4. A calibration confirmation will appear to show a successful calibration. Recalibrate if the symbol disappears. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B01GQVSQGG | | Best Sellers Rank | #17,764 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #21 in Lab pH Meters | | Brand | Bluelab | | Brand Name | Bluelab | | Container Type | Bottle | | Customer Reviews | 4.7 out of 5 stars 1,142 Reviews | | Included Components | One 500ml of ph4 and One 500ml of ph7 | | Item Form | Liquid | | Item Volume | 500 Milliliters | | Manufacturer | bluelab | | Model Number | BL-COMBO-1 | | Molecular Weight | 32.06 | | Molecular weight | 32.06 | | Package Information | Bottle | | Part Number | BL-COMBO-1 | | Unit Count | 2.0 Count | | Volume | 500 Milliliters | ## Product Details - **Brand:** Bluelab - **Item Form:** Liquid - **Item Volume:** 500 Milliliters - **Molecular weight:** 32.06 - **Package Information:** Bottle ## Images ![pH 4.0 & 7.0 Calibration Solution Kit - pH Meter & pH Pen Calibration for Balanced Nutrient Solution NIST Traceable | Hydroponics, Gardening & Growing Tents (500 ml/ 16.9 Fl Oz Each) - Image 1](https://m.media-amazon.com/images/I/71+ybs4c1zL.jpg) ## Questions & Answers **Q: Can you reuse solutions?** A: Yes a couple of times but I wouldn’t pour it back in the bottle if you’ve used it already. For example I have 3 ph meters so I’ll put some of each in a cup and use the same solution to calibrate all 3 of my ph meters then toss the solution. The bottles last a long time though. **Q: The bottle doesn’t specify how much solution to add to how much water to make the ph 7.0 and 4.0 solutions. It just says add the required amount???** A: You don't add anything its pre made to the ph level. **Q: Can i use this solution for other brand ph meters ? i own a adwa ph meter, or is this only for bluelab products ?** A: It will work for all PH meters. **Q: How often would I expect to run out of solution? I would hope for $45.00 this would last a t least a year.** A: I believe it will last a year I Calibrate my pen whenever it goes out of calibration which is usually about once a month ## Customer Reviews ### ⭐⭐⭐⭐⭐ Perfect *by M***J on October 25, 2024* I followed the directions to the letter and the calibration solutions worked perfectly. I feel so much better about my grow knowing the reading I am getting are true readings. The solution hand my Blue Labs OnePen with perfectly calibrated and fast results ### ⭐⭐⭐⭐⭐ Good *by S***N on March 10, 2026* Good ### ⭐⭐⭐⭐⭐ Works Well *by R***A on July 21, 2023* I own the blue lab ph pen and EC meter, and these solutions are perfect for calibration of the pH pen. I bought large bottles, still working super well a year later, probably have enough to last me another 3 years of regular monthly calibration checks/calibrations. Between the nice test pen and these solutions my hydroponic results have improved. Good stuff. ## Frequently Bought Together - Bluelab pH 4.0 & 7.0 Calibration Solution Kit - pH Meter & pH Pen Calibration for Balanced Nutrient Solution NIST Traceable | Hydroponics, Gardening & Growing Tents (500 ml/ 16.9 Fl Oz Each) - Bluelab STSOL120 KCL Storage Solution 120ml pH Probe and Pen, Maintain Meters Used for Water, Soil, and Hydroponic System or Indoor Plant Grow White --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.co.uk/products/32105900-ph-4-0-and-7-0-calibration-solution-kit-ph](https://www.desertcart.co.uk/products/32105900-ph-4-0-and-7-0-calibration-solution-kit-ph) --- *Product available on Desertcart United Kingdom* *Store origin: GB* *Last updated: 2026-06-25*