APERA INSTRUMENTS AI209 Value Series PH20 Waterproof pH Tester Kit, ±0.1 pH Accuracy
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Availability:
In Stock.
Arrives
Tuesday, Aug 4
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Style: Regular Kit
Features
- Easy auto. calibration with buffer recognition; auto. temp. compensation (ATC) ensures accuracy in various temperatures (32 to 122F)
- Backed by Apera quality pH sensor with low impedance, ensuring high response rate
- Comes in a rugged carrying case with pH 4&7 buffers and a lanyard
- Auto recognition of stable values improves consistency, so you don't have to guess when to manually hold measurement
- Up to 2000 hours' continuous operation, powered by AAA batteries
Description
Simply the most reliable pocket pH tester with the best value for general- purpose pH testing e.g. hydroponics, horticulture, pools and spas, water treatment, beverage making, education, environmental monitoring, etc. Up to 3 points of Auto. calibration and 0 to 50˚C Auto temperature compensation (ATC), 0. 1 pH Accuracy with 0 to 14. 0 pH measuring range; Auto. recognition and indication of stable values improves repeatability, saving you the trouble of guessing when to manually hold measurement. PH20 comes with a complete kit of premixed calibration solutions (4.00 and 7.00), 4 AAA batteries, and a lanyard all in a portable carrying case. Smart Self-diagnosis, warning of incorrect buffer solutions and incorrect calibrations. IP67 water-resistant. Up to 2000 hours' operation powered by AAA alkaline batteries. The product is CE and RoHS certified, and is manufactured under an ISO 9001: 2015 certified quality system.
Brand: Apera Instruments
Special Feature: Waterproof
Color: Regular Kit
Age Range (Description): Adult
Included Components: PH20 Value pH tester kit
Outer Material: Plastic
Specification Met: CE, ISO 9001, RoHS
Display Type: Digital
Product Care Instructions: Hand Wash Only
Unit Count: 1 Count
Additional Features: Waterproof
Display Type: Digital
Power Source: Battery Powered
Number of Batteries: 4 AAA batteries required. (included)
Upper Temperature Range: 50 °C
Response Time: 5 seconds
Reusability: Reusable
LowerTemperature Range: 32 °F
Indoor Outdoor Usage: Outdoor
Battery Life: 2000 hours
Outer Material: Plastic
Product Care Instructions: Hand Wash Only
Color: Regular Kit
Style Name: Regular Kit
Unit Count: 1 Count
Item Length: 21.8 centimeters
Brand Name: Apera Instruments
Age Range Description: Adult
Included Components: PH20 Value pH tester kit
Model Name: PH20
Model: AI209
UPC: 858718006339
Global Trade Identification Number: 39
Manufacturer: Apera Instruments
Warranty Description: Two-Year limited warranty for the instrument, Six-Month limited warranty for the electrode(s).
Item Weight: 3.9 ounces
Part Number: AI209
Specification Met: CE, ISO 9001, RoHS
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Aug 4
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Style: Regular Kit
“I’m really happy with this purchase! The quality is better than I expected, it arrived quickly, and it works exactly as described. It was easy to use right out of the box, and you can tell it’s well made. I would definitely recommend it to anyone looking for something reliable. Great value for the price!”
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Reviewed in the United States on July 29, 2026 by Nancy Ramos rizo
Style: Regular Kit
One evening after rearranging my little aquarium corner, I spilled my cup of iced tea while checking water parameters — and that’s when I realized I really needed a reliable tester. That’s when Apera PH20 Waterproof pH Tester Kit became part of my setup, and it’s been surprisingly reassuring to use. At first glance it feels like a simple pocket tester, but once you start using it, it’s clear it’s built with quality in mind. The digital display gives me a quick, readable pH value, and the automatic calibration and temperature compensation means I’m not second-guessing readings when I test different tanks or water samples. It’s IP67 waterproof, so splashes (or accidental drops) don’t stress me out when I’m checking water chemistry. I’ve used it on my aquarium water, plant reservoir solutions, and even my tap water tests, and it consistently gives results that match other meters I’ve checked against. The kit arrives with calibration solutions and batteries so you can start using it right away. A couple honest notes: You’ll want to calibrate regularly for best accuracy, especially if you’re using it often. The probe won’t last forever — like most glass probes, if you don’t rinse and store it properly the longevity can be limited. Overall, it’s a dependable and easy-to-use pH tester that’s worth having if you’re checking water quality for aquariums, gardening, hydroponics, or general water checks. Easy setup, solid accuracy for the price point, and the waterproof design make it feel like a tool worth keeping in your gear bag.
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Reviewed in the United States on February 23, 2026 by SAM
Style: Regular Kit
This pH meter is great! Much better than the Bluelab meter that is twice the price of this one. The calibration was easy. I like how fast it gets to the correct pH, which saves me time when mixing feeding solutions for my garden.
Reviewed in the United States on June 18, 2026 by Patricia
Style: Regular Kit
I bought this tester mainly to verify two cheaper ones I had already. I was just not confident the ones I was using were giving me accurate readings. When I tested them with calibration solution they both read slightly off one being higher and one lower. So I decided to spend the money on a higher end model. The Apera model seems to work very well and when tested in calibration solution is usually spot on. It has a nice LCD display which is easy to read during normal operation and is much quicker at determining the PH level versus the cheaper ones where you need to wait a while for them to stabilize and typically have much smaller and darker displays. That is the good news, however, the calibration procedure is a bit clunky compared to even the other cheaper ones I have. Partly due to the instructions which are very poorly written, hard to follow and provide contradictory information when it comes to things like storing the device. I understand it was made in China but for gosh sake, hire someone who knows how to speak and write in English to design the manual so it makes sense. In my application PH is very important so having more than one tester is not a bad thing. But it I had to pick just one and price was not an issue....then yes, I would chose the Apera model, but by a very small margin. Mainly because it appears to be a higher quality, well made device - even though the included instructions and funky calibration procedure hold it back from a five star rating. But in the end it is only slightly more accurate then the $10-$15 ones I already have. If the accuracy of the PH reading is that important to you and you want the best and do not care about spending $50, then the Apera is a fine choice. But if you are on a budget and are using a tester to check the PH of say swimming pool water, a cheaper model will work just fine. I would recommend getting two cheaper units from different manufacturers so you can check them against one another. You will spend about half of what it cost for the Apera. And as long as you occasionally test and re-calibrate them, you are better off with two cheaper models than the one more expensive one that does the same thing.
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Reviewed in the United States on June 19, 2021 by E. A. Jacques
Style: Regular Kit
I bought the Apera AI209 Value Series pH Tester for use in our professional kitchen, mainly to test the pH levels of barbecue sauces and hot sauces to ensure they stay below the required threshold for shelf stability. It’s been a fantastic upgrade from our old Dr. Meter testers, which were cheaper upfront but rarely lasted more than three months and were frustrating to keep properly calibrated. The calibration process with the Apera is a breeze. Unlike other brands that give you powder packets you have to mix with “clean” water (and good luck deciding what counts as clean), this kit comes with bottles of perfectly balanced calibration solutions; no guessing, no inconsistencies, and no cursing over cloudy mixes. You start with a solid, reliable baseline right out of the box. Readings are quick (usually within 5 to 10 seconds), and the included carrying case is surprisingly sturdy and well-organized. It's been dropped a few times already. I know this pH tester is marketed toward a wide range of uses, but for food safety applications in a commercial kitchen, it’s been excellent. It gives us accurate, repeatable results, and peace of mind knowing our sauces are safe and shelf-stable.
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Reviewed in the United States on October 25, 2025 by TC
Style: Regular Kit
I recently purchased the Apera Instruments AI209 Value Series PH20 Waterproof pH Tester Kit, and it has been an absolute game-changer for my home gardening and aquarium maintenance. It arrived quickly and in perfect condition, thanks to Amazon’s reliable packaging. The box included everything promised: the pH meter, calibration solutions, storage solution, and a detailed manual. Right out of the box, the pH tester felt solid and well-made. The design is compact and ergonomic, making it comfortable to hold and use. Setting it up was straightforward. The instructions were clear, and calibrating the device with the provided solutions was a breeze. It only took a few minutes, and I was ready to start testing. What I love most about this pH tester is its accuracy and consistency. I've used it to test the pH levels in my hydroponic system and aquarium, and the readings have been spot on every time. The device is very responsive, giving me quick results that I can rely on. The backlit display is bright and easy to read, even in low light conditions, which is a nice touch. Another standout feature is its waterproof design. I’ve accidentally splashed it a few times while working with my aquarium, and it’s held up perfectly. It’s reassuring to know that it’s built to withstand such mishaps without compromising its functionality. The automatic temperature compensation is another fantastic feature. It ensures that the pH readings are accurate regardless of the temperature of the liquid being tested. This is particularly useful for my aquarium, where water temperature can vary slightly throughout the day. Battery life seems excellent so far. I’ve used it quite a bit over the past few days, and there’s no sign of it needing a replacement anytime soon. The device also has an automatic shut-off feature to save battery, which is always appreciated. Overall, I’m extremely pleased with the Apera Instruments AI209 pH tester. It’s reliable, easy to use, and very accurate. Whether you’re a home gardener, aquarium enthusiast, or just someone who needs to measure pH levels regularly, this device is a fantastic investment. Highly recommended!
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Reviewed in the United States on June 21, 2024 by rick k
Style: Regular Kit
Great pen for the price
Reviewed in the United States on June 19, 2026 by Kindle Customer
Style: Regular Kit
This thing is advertised to work for general liquid solutions. Unfortunately, be aware it does not read water. Yeah, you read that correctly. You need enough stuff IN the water, or it will not read the water. I use reverse osmosis water for my plants, and it is "empty." I add nutrients to it, but it takes a LOT of stuff in the water before you get an accurate reading. To make matters worse, it will not tell you when it is doing this. You will have no idea. I suddenly thought there was something wrong with my R/O water causing it to be extremely high pH. No, it was not the water; the water was still the same old 5.5 pH it always was, but the pen COULD NOT read it properly and was telling me 8 pH. THERE IS NO MENTION OF THIS anywhere before you purchase it. It is not mentioned in the instructions either. Therefore, I trusted the meter (which works phenomenally otherwise) and completely ruined months of work. Additionally, I often want to water my plants with water that is at the right pH of about 6.5, but does not have ANY nutrients. This is common, called a "flush," because you don't want to keep feeding nutrients to plants that don't need it. Well, you can't measure water with this, so I can't do that. For the high price, it works great, but it does NOT work in all situations, and they make little effort to warn you of this. Now I have to buy one that costs twice as much??? This is stupid. So now I am left to bumble around confused using both this and the pH strips I was trying to get away from. Now I need yet another unit that will measure empty water. I had a $5 one that did it, which I threw away once I got this, thinking I would no longer need it. This seems absurd to me. I guess I am one of the few people using reverse osmosis water or something? I think I deserve a refund or upgrade to a version that will WORK, but I doubt I'll even get a response, and if I do, the responses will just blame me instead. My ignorance isn't my fault if you don't make an effort to alert me before purchase. And don't tell me to do more research. I DID research.
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Reviewed in the United States on February 28, 2021 by JDW