American MarinePINPOINT pH Monitor + Calibration Fluids

Finally an accurate PH tester. the calibration method on this is a little bit of work compared to an auto calibrated unit, but THATS WHAT MAKES IT WORK so well. just stick it in the 7.0 liquid and 10.0 liquid back to back to back to back until it reads right by adjust the screw. little tip, you need a tiny flathead, a regular flathead wont work. dont be put off by the calibration its really simple. just takes like 5-10 min then your good to go with the most accurate reader thats actually reliable. and you can just permanently leave it in your tank too! you do need a 9volt battery

I have been using these Pinpoint monitors for several years. They are always very dependable. I use to monitor the pH in my CO2 injected planted tank. Works great. Wish they had a controller version as well but this monitor is on 24x7 and allows me to constantly monitor my tanks PH. Highly recommend.

Advantages: Fairly quick: reading stabilises in 30 seconds or less. Holds its calibration pretty well ( I store the probe in 3M KCl). [I'm only using it on solutions with pH between 7 and 10 so I can't comment on its use outside this range.]Disadvantages: There is no 'automatic' calibration, manual calibration is slow, and the two calibration screws work in opposite directions (the pH 7 screw turns clockwise to increase pH reading, the pH 10.01 screw turns anti-clockwise to increase pH reading) which can cause wasted time if you forget. The cable which connects the probe to the measurement unit is unscreened so if you are not careful it is significantly affected by the static from your body - you can see the reading change as you move closer or further away. So you must ensure the cable is completely uncoiled to prevent any induction effects.Update: I originally rated this 4 stars but the more I used it the more I liked it. I just ordered my third one! Now that I'm familiar with the manual calibration it goes fairly quickly and you can end up with a much more accurate result than the 'automatic' ones. The accuracy and repeatability are very good for the price.

I carefully followed the calibration instructions for this machine using the provided calibration liquid, and I quickly realized how sensitive the wires are to any touch! Just the slightest movement can affect the readings. After nearly an hour of focused effort, I finally got it to show 7.0 in the 7.0 liquid and 10.0 in the 10.0 liquid. What a relief to see that it was calibrated!However, when I placed the probe in my tank, I felt a little uncertain about the reading. To get a better understanding, I decided to verify its accuracy with my Redsea test kit. To my surprise, the probe's reading was significantly off. I thought maybe my Redsea kit could be the culprit, especially after all the time I had invested in calibrating this machine, so I tried a different test kit too.Both my pH test kit and the Redsea test kit confirmed the same results, while the probe continued to give an inaccurate reading. Although it's disappointing, I feel it's best to return this machine and explore better options!

I've tried the $10 meters and the $50 meters and they were all crap. Even the $50 ones are inaccurate and don't calibrate well. This meter keeps its accuracy for about a month, and even then it's only off maybe +/-.1. Easy to calibrate. I dropped the whole unit in water, dried it out, and it still works perfect. Don't waste your money on cheaper ones, this is the one you want.

running 24/7 in salt water tank only have to check the calibration monthy and is always with in 0.05 which is good for what I need to check. Calibration takes some time, that's way I only gave it 4 starts

Not really worth the money. Once calibrated, this pH monitor works well enough for the next use, but for point point accuracy (within the manufacturer's estimate) it requires calibration before each use. I think that this ph monitor is best for use in an aquarium, a pool, hydroponics, or in any situation in which you need to monitor ph constantly without removing the probe from the liquid. It does not work so well as instrument used to measure the ph of different liquids by dipping the probe into each liquid because it seems to require calibration each time it is used on a different liquid.To be honest, for most uses, you would be better off using litmus paper strips, or a chemical test.*Update: For a while, the device performed well enough and gave stable readings, providing that it was calibrated before each use, but after nearly six months of use, it started giving spurious readings and obviously incorrect results, and even calibration did not help. For example, even when properly calibrated, it gave three different readings for a sample of white vinegar (ph 2.3) with readings ranging from 1 to 14. Sometimes the reading fluctuates so wildly that it is impossible to even get a reading of the ph of a gallon of tap water (which for my location ranges from ph 7.5 to 8.5). Sometimes, if I were to believe this device, hydrochloric acid is pumped out of my faucet by the water company! Yet sometimes it is very accurate when tested against a known ph or another method of measuring ph.I suspect that the device itself works well but the probe is fragile and unstable, and needs replacement. I have bought a replacement probe (2/1/15) and will see how that performs. I'll update this review after I've calibrated and tested this new probe for a while.