Thats all it does. Short press turn on. Says USA long press now USA flashes. Says p1. Soak in 7ph solution. Does nothing. Flashes USA. No ph reading. Nothing. Wasted 15 minutes for nothing! Says rinse with water and dry. All this bantering to read. Why. To waste more time with this irritating thing for nothing? Sending it back. Later. Pulling it backout of it's clumbsy cumbersome box it was on. Reading ph now by some miracle act of god. It thinks the 7ph test solution is 6.9ph. Drained another 10minutes of my life for nothing trying to follow the sensless calabration directions.Telling me over and over and over again to rinse it in tap water and soak it for 5 minutes. Hopeing I die from old age or it's warrantee runs out. It says p1. Smiley face p2 p3 does norhing it's supposed to. It doesnt just fire up and read ph. Ohh no. You have to play games with it. Then when you put it down and stop playing with it. Give up. It starts working. The 7ph test solution reads 6.9ph. I can live with that. Balanced my nose spray to perfect 7ph as it reads 6.9ph. Fine. It works. It will always read 6.9ph likely. I'm not waste another millisecond of life considering calibrating it. I'll turn it on. Dip in 7ph provided solution. Whatever it says I'll balance the nose spray to that. Big clumbsy and cumbersome. Pour nose spray beaker into it's lid sensor cap take test sample. It's to grossly oversized to fit the beaker itself. It's calibration functions dont function. But it does read ph to the tenth. Way better than test strips. My 1st meter. Seems way overpriced. I'll keep it though. Until I get a better smaller less irritating one. Should deduct one star cause it don't play its little calabration game fair and reward when I push its little buttons correctly. And way overpriced. But it's my 1st one and it so much more accurate than test strips. rewarding me with great nose spray balanced correctly for the 1stime. Had to fight it the every inch of the way. it won't last very long. Its reloading.

This unit is great. So simple to use and calibrate. Holds calibration for quite a while but other then the initial testing, I calibrate every few uses just because I want to. The LCD screen is easy to read and the instructions that come with the kit are simple to follow and well thought out. Speaking of the kit, it has everything one needs to calibrate. Comes in a nice foam lined carrier as well. This Apera has proven to be accurate and reliable and I would definitely purchase again.

I use this every day. I also calibrate it with the proper pH solutions every month. Easy to use, very well made, excellent operating instructions (including an illustrated laminated card. If I could add one improvement, it would be to have grippy ridges molded jnto the sides of the meter to minimize it slipping out of one's hand. The storage/carrying case is very well made also, with padded cut-outs to fit the instrument and two bottles of calibrating solution. This is a superior product.

This meter is great, it's got clear instructions, allows you to calibrate to +/- 0.1pH For the low and medium sections of the pH scale using the included 4.00 pH buffer solution and the 7.00 pH buffer solution. To calibrate the high end of the scale you will need to purchase/provide a 10.00 pH buffer solution separately.

The sensor works fine for low (1 to 5?) and medium (around 7) pH, and indicates on screen which sections of the scale have been calibrated.

Very stable for the past two days of usage, no drift at all vs the reference solution, and I've used it about 10 times.

Case is nice. Instructions say to replace the buffer solutions after 10 to 15 calibration uses.

Easy to read LCD with temperature readout. Be sure to read ALL of the instructions though, there are important tips and best practices.

This is the best pH pen I've owned yet. The value here is understated considering all you get. I was pleasantly surprised that the calibration solution were thoughtfully designed with end user in mind. The unit itself is waterproof, which places it into another category altogether. Many waterproof units are much more expensive. I have not had to calibrate it since the 1st time. I'm not sure if I like the vertical display better than the typical horizontal display that a traditional pen uses but this unit provides a lot of useful info that is easy to read on this larger screen. Also, it has been very accurate so far. I have an HM digital pen that has been good for a while but I do have to calibrate it from time to time where this one seems to have maintained its accuracy for several months.

I would recommend this to everyone.