Review on 🌡️ Household Resolution Temperature Calibration in AMTAST by John Swain

Pros: Stylish design, easy to store away when not in use. In theory, it's ready to use right out of the box. Cons: There's just no way to know for sure if it's accurate in the absolute sense. Discussion: I've spent a lot of time looking for a product that displays results in LEDs. mode, but also did not require "calibration" before use. I just didn't want to invest in distilled water or commercial buffer solutions. However, upon arrival, right in the manual, one can notice that there is a whole section dedicated to calibration, recommended only for professional users. It would be sufficient to simply ignore the paragraph and only use the pen as recommended. However, for convenience, the LED screen is almost always in "CALI" mode by default, requiring a second click before it makes the correct display. So the process does not inspire confidence. Out of frustration, I tried following the calibration instructions with tap water, which I know from experience is pretty close to 7.0 ph. And I regularly checked the results against my old-fashioned liquid pH indicator. The two results matched pretty closely, but to be honest the reason I wanted to switch to LED readings was so I didn't have to constantly read subtle shades of green on a color chart. SUMMARY: If all you want is a digital readout that gives you a general idea of whether your tank's pH is rising or falling (and alternately shows you the water temperature in Celsius) then this product might be for you. But if you're looking for absolute certainty within a few decimal places, I'd only give it 3 stars out of 5. EDIT: Over the past few days I've found that the display modes are highly dependent on how long you hold the power button. Long press (15 seconds or more) enters calibration mode; a short press results in a stable reading once it stops flashing. I'm giving 3 stars mainly because the on/off button is tiny, flat and hard to press. This is really my pet at the moment.