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Apera Instruments

APERA INSTRUMENTS AI209 Value Series PH20 Waterproof pH Tester Kit, ±0.1 pH Accuracy

Based on 8,927 reviews
Condition: New
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$56.65
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Availability: In Stock.
Fulfilled by Amazon
Arrives Friday, Nov 13
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At a glance

Condition
New
Style
Regular Kit
Model
PH20
Weight
3.9 oz
Special Feature
Waterproof
Outer Material
Plastic
Specification Met
CE, ISO 9001, RoHS
In the box
PH20 Value pH tester kit
Warranty
Two-Year limited warranty for the instrument, Six-Month limited warranty for the electrode(s).

Features 5

  • 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

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.

Specs 29

Brand Apera Instruments
Special Feature Waterproof
Color Regular Kit
Age Range (Description) Adult
Outer Material Plastic
Specification Met CE, ISO 9001, RoHS
Display Type Digital
Product Care Instructions Hand Wash Only

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Friday, Nov 13

Yes, absolutely! This item's return window has been extended for the holiday season: FREE refund/replacement until Jan 31, 2027.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

Highly recommend
Style: Regular Kit
Just as good as bluelab half the price. Very reliable and stable and easy to use. pH is on point
Reviewed in the United States on August 15, 2026 by Trenton Arnold
Best bang for your buck.
Style: Regular Kit
I love this ph pen with just a few complaints . Seems to be the most accurate I have used . This is my third one. I also just purchased the ac infinity ph pen which I swear is made by the same company but it has a replacement head. But it’s always a point and a half off compared to my two aperas that I double check everything with. So I’ll probably be contacting them to see what’s going on or taking it as a loss and sticking with these. For the quality you get I feel like price is fair . Just bought the tds too so I’ll be checking it out over the next few weeks. Be careful the glass bulb is very thin and easy to break when cleaning. My fault though. I was using the wrong thing to clean with and now I use old nylon paintbrush’s for watercolor and those stiffer bristles seem to clean very well. ... show more
Reviewed in the United States on August 15, 2026 by Justin
Accurate, reliable, and perfect for professional kitchen use.
Style: Regular Kit
Review Image by TC
Review Image by TC
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. ... show more
Reviewed in the United States on October 25, 2025 by TC
Accurate and Easy to Use - But do you Really Need to Spend $50?
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. ... show more
Reviewed in the United States on June 19, 2021 by E. A. Jacques
Love ir
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!” ... show more
Reviewed in the United States on July 29, 2026 by Nancy Ramos rizo
Affordable meters at blue lab quality without the ridiculous price tag.
Style: Regular Kit
I have been using Apera PH meters for a decade. I just bought this new ph meter as well as a tds meter to go with it. The first finally after almost 10 years of abusive use, but never had an issue until my size 11 found it on the ground while carrying 2 bags of coco loco, Mt 185 plus the 40 extra pounds from the bags and the poor meter finally lost the battle. 10 years? Any meter that lasts that long staying in calibration is well worth it's salt, and Apera makes products well worth their salt. I'd highly recommend these meters, especially if your a grower, the quality is unbeatable for the price. I'd say their customer service is great too but I've never had a reason to contact them, but qualityand affordability are no accident, so id better their people are as solid as their meters. If your having trouble deciding on one of these because there are thousands id guess for sale on here, but the no brainer is Apera meters. ... show more
Reviewed in the United States on October 6, 2026 by Rob Radcliff
dependable and easy-to-use pH tester
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. ... show more
Reviewed in the United States on February 23, 2026 by SAM
Wish I'd known this. Great, if it works, but it DOES NOT MEASURE EMPTY WATER.
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. ... show more
Reviewed in the United States on February 28, 2021 by JDW
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