Hanna InstrumentsHI98128 pHep 5pH/Temperature Tester, 6-25/64" Length x 1-19/32" Width x 1" Height

I'm a homebrewer and I got one of these for measuring the pH of my grape must. I'm also a cook and a physicist and I like being able to measure the pH of lots of things. This is a nice balance between price and accuracy. This is probably as accurate as you would need for any household application. You need to have a buffer solution to store it in and you should have two solutions for calibrating. It's not trivial to use properly (you should read the manual) but it's not difficult either.

Taking my local extension Master Gardner program we used these to do soil tests. Since then I have started my own lawn care company and I tried cheaper ones with very inconsistent results. The Hanna works very well, plus they have headquarters only a few miles from me!

When your whole aquarium relies on these two fundamental elements you don't really need anything else. Calibration is easy. You get a reading in 15 seconds. Easy to keep an eye on your tank.

Worked OK for about 2 months, although readings fluctuated during this time. Then the fluctuations got worse until now it is impossible to re-calibrate and the readings are incorrect everytime. The product is fragile and I wouldn't recommend buying.

I have been using the Hanna pH/Temperature tester for two months now. It gives relatively accurate readings, and is easy to use, and calibrate (using the calibration solutions...sold separately). I keep mine submerged in a balanced salt solution. It is critical to keep the electrode hydrated at all times. If it should dry out, the life of the electrode will lose its accuracy, and may have to be replaced. I use mine to gauge the acidity of cheeses that I am making from milk products. The reason I only gave it a 4/5 is because you must recalibrate it after4 each usage. You must also purchase the standardizing solutions separately....an expensive proposition in the long run. But, I would purchase this model again.

works well for an entry level ph testing pen. This is less than half the price of the next model up, and tho it may not have all the same features, this pen reads as accurately as pens many times the price. great value

I have used the HI 98121 and now the HI 98128. The 98121 I bought was very slow. It wasn't until I bought and used the 98128 that I realized how fast it should have been. The two big negatives for Hanna is their customer service won't necessarily give you the correct answer to any questions and the fact that it is very hard to keep the pH probe moist at all times with the design of the cap.The cap is not liquid tight, so when you put a few drops of storage solution in it, if you don't keep the meter upright at all times, the storage solution will drain out. Plus, it's a very small resevoir, so you have to constantly top it up. Very poor design for a critical function.If you get a properly functioning meter and keep the probe moist with storage solution, it will perform very well. The meter is advertised as being water *proo*, but I was told by a support person that I should not submerge it to a depth of 18", whihc is where you should sample your water from. I can say that even though he said that, I used the 98121 for about 6-7 years before the seals failed and I always submerged it to at least 18" and sometime as deep at 36".All said, it is so much easier to keep you pH at a consistent level with a meter, rather than a drop test. It's measures down to 2 decimal places which allows you to see what direction your pH is headed before it gets out of hand. The drop tests are graduated in whole numbers of 2 points, ie:70, 72, 74, 76, etc..Using a pH meter has made keeping my pool clear and balanced a much easier job.

I'm extremely happy with Hannah, their customer satisfaction is amazing! Their ph meters r awesome and they r pretty damm accurate!