Apera Instruments AI103G GroStar Series GS3 EC/500ppm/700ppm Pen Tester Kit with Replaceable Titanium EC Probe for Hydroponics Water Quality Testing, Gen II

While it is one of the more expensive options for testing these parameters, the GS4 is very high quality, easy to calibrate and east to use.Their customer service is also great. I accidentally broke the plastic clip/cap through my own carelessness and the sent me a new cap at no charge. They’ve also helped me rehab the device after I accidentally dropped it in the 5 gallon hydroponics bucket. I know, I need to be more careful.

Perfectly calibrated out of the box. The pH meter is incredibly accurate and agrees with pH paper test strips! I had purchased another Apera meter (Apera Instruments AI311 PH60) thinking that I could use one of those cheap meters for EC but it was inaccurate and junk, wouldn't auto shut off and was a total waste of money and time. I had already wasted time and money on the cheap pH meters that were awful to calibrate, used expensive small button batteries, did not shut off automatically so it was 1 reading and new batteries if you don't shut them off. By mistake, I purchase 2 identical cheap pH meters and they won't even agree with each other for pH or EC and they don't agree with either of the Apera meters (both of the Apera meters agree perfectly on pH) or pH paper test strips. I don't have any thing to compare the EC meter with but from my experience with the pH portion, I would expect it is extremely precise and accurate.Would be nice if the GS4 came in a similar case to the PH60 instead of a cheap cardboard box that won't last.

I bought a GS4 more than a year ago. I can't remember where I bought it so I can't pen down exactly when I bought it, but I suspect I've been using that first one for a couple of years at least. I bought this second one from Amazon as a back-up to the first one.A few months ago, because I am an expert at all things electronic, I put the batteries to the first one in backwards. In just a few seconds the whole thing heated rapidly. Very hot. Very rapidly. I happened to be holding it at the time, and I can attest to this.I rely on the results I get from the GS4, and I was relieved to see that once cooled, it calibrated as always and returned consistent results within tolerance. Your mileage may vary. I bought this second unit from Amazon as insurance against any further operator error.What spurred me to go ahead and get another just in case is that realized how much I depend on this pen. I spent way too much money trial-and-erroring my way to this meter. I suggest anyone who buys this pen to get qt bottles of standard solutions (4,7,10, 2.7), a qt of cleaning solution, and a pt of KCL. They're relatively cheap at that size, and cleaning/calibrating/storage becomes almost economical. This is a dependable, reliable instrument that's worth the trouble and expense of maintaining it.

Very accurate. Tested against my blue lab and it actually read quicker than the blue lab. Excellent. Now all I need is longevity!!

The media could not be loaded.  Amazon shipping, not bad, 7 days.The GroStar GS4 is a fantastic all in one pen that I'm absolutely loving. I have always used 2 pens to get my ph/ppm readings which was a bit of a pain juggling & maintaining them both constantly. Now with the GroStar everything is a click away while reading temperatures at the same time too. *Long press bottom button to switch from Ferinheight to Celcius. One of the great features I really like about this Apera pen is you only have to relace the probe when its expired not the whole pen! Good engineering!The screen is bright and easy to read and understand. Calibrating the whole pen takes about 90 seconds tops, its very easy. I have uploading a quick video of how easy it really is. I see some user error in some of the problems some people are having. The GS4 is quality, It's a great value for what you get Imo.Great job with this new GroStar lineup 👍👍I would recommend this pen all day long to all growers, give it a try, I think you will be happy👍🍅🍅🍅🍅🍅

Easy to use. Really enjoy it. Kits comes with all you need. Also has the options to buy replacement probes down the line.

Wanted to like this because it would be so much easier versus using the paper pH strips but this model (or maybe just the one I received) was not reliable at all. Even the readings were far off what my pH strips showed. I did all the troubleshooting and resetting several times. I ended up sending it back because I needed to get my water right in a timely manner and went back to the paper pH strips.

Simple straightforward tool. Not as advanced as the pc60 but for basic plant growth and gardening is definitely enough. My pc60-z has the app functionality which is great and it also reads in the hundredths which the grostar gs4 don’t but for all it’s worth it’s no needed. These serve well for the daily use and I can always check a nutrient solution against the pc60. I have two grostar one for indoor and one for outdoor. Thanks for the nice tools again apera

Kalibrieren ging sehr schnell von der Hand. Toll, dass man den Sensor austauschen kann. Die Ergebnisse sind immer gleich nach mehrmaligen Tests. Somit gebe ich meine Empfehlung für dieses Gerät.Aber zu dem Preis erwarte ich mir eine bessere Verpackung. Habe einen alten pH Messer von apera , der hat wenigstens einen wunderschönes case dabei. Für mich unverständlich bei diesem Preis. Leute wenn ihr das Geld nicht dafür habt, könnt ihr auch genauso einen wertigen ph-ec temperaturmesser bekommen, wo ihr auch ebenfalls den Sensor austauschen könnt. Name: Aqua master p110 pro Combo. Über ein like freue ich mich immer.