--- product_id: 231974651 title: "Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow)" brand: "ruolan" price: "¥3405" currency: JPY in_stock: true reviews_count: 13 category: "Ruolan" url: https://www.desertcart.jp/products/231974651-digital-ph-meter-tester-pen-for-water-pre-calibrated-high store_origin: JP region: Japan --- # pocket-size portability ±0.01 high accuracy 0–14 pH full range Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) **Brand:** ruolan **Price:** ¥3405 **Availability:** ✅ In Stock ## Summary > 💧 Your personal water quality guru—precision testing, anytime, anywhere! ## Quick Answers - **What is this?** Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) by ruolan - **How much does it cost?** ¥3405 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/231974651-digital-ph-meter-tester-pen-for-water-pre-calibrated-high) ## Best For - ruolan enthusiasts ## Why This Product - Trusted ruolan brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Ready to Use Out of the Box:** Pre-calibrated for instant testing—skip the setup and start monitoring your water quality immediately. - • **Sleek, Compact & Travel-Ready:** Slim, lightweight design fits effortlessly in your pocket or bag—test anywhere, anytime. - • **Lab-Grade Precision in Your Pocket:** Experience ultra-accurate pH readings with ±0.01 precision—no more guessing, only confidence. - • **Versatile Water Testing Powerhouse:** Perfect for drinking water, pools, aquariums, hydroponics, and RO systems—one tool for all your water needs. - • **Intuitive Operation with Bright Display:** Simple one-button use and a clear screen make testing fast and foolproof, even in low light. ## Overview This Digital pH Meter Tester Pen delivers lab-level accuracy (±0.01) across the full 0–14 pH range in a sleek, pocket-sized design. Pre-calibrated for immediate use, it offers fast, reliable readings for drinking water, pools, aquariums, and hydroponics. Its intuitive one-button operation and bright display make water quality monitoring effortless wherever you go. ## Description Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow): desertcart.com: Industrial & Scientific Review: Aquarium and House Plants--Water Testing - This is my third pH meter from a different manufacturer and happy that I took the chance to try this out. All three meters that I have bought have different maintenance instructions. I've been comparing them to find out what works best. The Apera brand has better instructions that are easy to understand and seems to work best. But it costs significantly more. This Roulan is the least expensive brand that I could find. Yet it functions acceptably for its price. The Apera is better in that it achieves the final stable reading faster and maintains calibration longer Review: Handy little ph meter - So I finally got one of these little digital pens to check my water and honestly it has made me feel like a total scientist in my own kitchen. I used to just stare at the tap and wonder if everything was okay but now I can just dip this in and see the numbers pop up right away 💧 It is basically like having a tiny expert living in your drawer who tells you exactly what is going on with your drinks so you dont have to guess anymore. I was actually suprised by how fast it works because I thought it would take ages to get a reading but it is usually done before I can even finish humming a little tune. It is super light and thin too which is great because it doesn't take up any space at all and I can even take it with me when I go to visit my parents 🏠 You just pop the cap off and stick it in the glass and then boom you have all the info you need right there on the screen. I accidentally left the cap off for a few hours once and I was worried I broke it but I just rinsed it off and it kept on working like a total champ. The best part is that the screen is really bright so I can even use it in the morning when I am still half asleep and havent turned all the lights on yet ☀️ I basically just point and click and it handles all the complicated math for me which is perfect since I am definitely not a fan of doing science experiments before I have had my coffee. It fits right in my pocket too so I can even use it to check the water at the gym or when I am out on a long walk in the park. If you are someone who likes to know exactly what is going on with your hydration then this is basically a little dream come true 🥤 Just make sure you keep the sensor clean or you might get some funny readings that make you tilt your head in confusion. I am honestly thinking about getting one for my friend who has a huge aquarium because it is so much easier than those messy drop kits with all the different colors. It is just a fun little tool that makes my daily life feel a lot more organized and I think you would really enjoy how simple it makes everything feel 🌟 It is basically like a magic wand for your water glass which is pretty cool if you think about it. I am very happy with it and I think it is going to stay right next to my favorite mugs for a very long time. ## Features - 【Calibration Operation Guide】 Press and hold the CAL button for 5 seconds to access calibration mode. Complete calibration by selecting the standard powders in this exact order: 6.86 → 4 → 9.18. Please refer to our full calibration instructions and tutorial video for detailed steps. - 【Pre-Calibrated for Immediate Use】The pH meter is pre-calibrated before shipment and can be used directly out of the box. For best accuracy, readings may vary slightly depending on water conditions and environment. - 【Easy Operation】Simply turn on the device, immerse the probe into the solution, gently stir, and wait for the reading to stabilize before recording the result. - 【Compact & Portable Design】Pocket-size design allows easy carrying for testing anytime, anywhere. Suitable for home, travel, and outdoor use. - 【Multi-Purpose Water Testing】Ideal for drinking water, swimming pools, aquariums, hydroponics, RO systems, and other environments requiring pH monitoring. ## Technical Specifications | Specification | Value | |---------------|-------| | Customer Reviews | 3.9 out of 5 stars 11,557 Reviews | ## Images ![Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) - Image 1](https://m.media-amazon.com/images/I/61BUiZjq72L.jpg) ![Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) - Image 2](https://m.media-amazon.com/images/I/71nlnulzyOL.jpg) ![Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) - Image 3](https://m.media-amazon.com/images/I/71nuMxLcmjL.jpg) ![Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) - Image 4](https://m.media-amazon.com/images/I/71ARcb1tWJL.jpg) ![Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0–14 pH Range, Pocket Size for Drinking Water, Pool, Aquarium & Hydroponics (Yellow) - Image 5](https://m.media-amazon.com/images/I/718yHTTwlzL.jpg) ## Available Options This product comes in different **Color, Size, Number Of Items** options. ## Questions & Answers **Q: How do I get warranty support? I have had this for 3 months and it quit working, just shows zero with an occasional flash of random numbers.** A: It's the horrible design in the battery tray. The pressure that keeps the metal contacts down also lifts the entire battery tray away from it's case making it lose contact. You can try to press them back but it will only happen again. **Q: can i get more Calibration powder?** A: Yes, available on Amazon. I use liquid ph 7 which I think is more economical and much simpler to use. **Q: where are the batteries? it says included. are they installed inside? Mine won't turn on** A: Yes they are installed. They are most likely dead, both meters I received came with dead batteries. The thin black cap comes off if the push in the release on the back and pull it up. **Q: Can this be used to test the pH of automotive coolant in your radiator??** A: Yes. It’s a general liquid ph meter ## Customer Reviews ### ⭐⭐⭐⭐⭐ Aquarium and House Plants--Water Testing *by P***L on March 25, 2026* This is my third pH meter from a different manufacturer and happy that I took the chance to try this out. All three meters that I have bought have different maintenance instructions. I've been comparing them to find out what works best. The Apera brand has better instructions that are easy to understand and seems to work best. But it costs significantly more. This Roulan is the least expensive brand that I could find. Yet it functions acceptably for its price. The Apera is better in that it achieves the final stable reading faster and maintains calibration longer ### ⭐⭐⭐⭐⭐ Handy little ph meter *by S***S on December 30, 2025* So I finally got one of these little digital pens to check my water and honestly it has made me feel like a total scientist in my own kitchen. I used to just stare at the tap and wonder if everything was okay but now I can just dip this in and see the numbers pop up right away 💧 It is basically like having a tiny expert living in your drawer who tells you exactly what is going on with your drinks so you dont have to guess anymore. I was actually suprised by how fast it works because I thought it would take ages to get a reading but it is usually done before I can even finish humming a little tune. It is super light and thin too which is great because it doesn't take up any space at all and I can even take it with me when I go to visit my parents 🏠 You just pop the cap off and stick it in the glass and then boom you have all the info you need right there on the screen. I accidentally left the cap off for a few hours once and I was worried I broke it but I just rinsed it off and it kept on working like a total champ. The best part is that the screen is really bright so I can even use it in the morning when I am still half asleep and havent turned all the lights on yet ☀️ I basically just point and click and it handles all the complicated math for me which is perfect since I am definitely not a fan of doing science experiments before I have had my coffee. It fits right in my pocket too so I can even use it to check the water at the gym or when I am out on a long walk in the park. If you are someone who likes to know exactly what is going on with your hydration then this is basically a little dream come true 🥤 Just make sure you keep the sensor clean or you might get some funny readings that make you tilt your head in confusion. I am honestly thinking about getting one for my friend who has a huge aquarium because it is so much easier than those messy drop kits with all the different colors. It is just a fun little tool that makes my daily life feel a lot more organized and I think you would really enjoy how simple it makes everything feel 🌟 It is basically like a magic wand for your water glass which is pretty cool if you think about it. I am very happy with it and I think it is going to stay right next to my favorite mugs for a very long time. ### ⭐⭐⭐⭐ Slow to the point *by K***Y on March 3, 2026* So I bought this product back in September and wanted to do a review after I’ve used it a bit. So it does eventually give me a result it just takes a couple minutes for an accurate result and sometimes even shuts before stopping at a number. ## Frequently Bought Together - PH Meter for Water Hydroponics Digital PH Tester Pen 0.01 High Accuracy Pocket Size with 0-14 PH Measurement Range for Household Drinking, Pool and Aquarium - General Hydroponics pH Control Kit For A Balanced Nutrient Solution - FoxFarm Fertilizer Soil Trio Liquid Nutrient: Tiger Bloom, Grow Big, Big Bloom Bottles - (Pack of 3-1 Pint) --- ## 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.jp/products/231974651-digital-ph-meter-tester-pen-for-water-pre-calibrated-high](https://www.desertcart.jp/products/231974651-digital-ph-meter-tester-pen-for-water-pre-calibrated-high) --- *Product available on Desertcart Japan* *Store origin: JP* *Last updated: 2026-07-21*