Free sulphur, pH, TA meters
Recently my Hanna HI 98128 ph meter dried out on me from sheer neglect*. Replacing the probe was almost as expensive as buying a new meter. Time to check out the latest and greatest.
Here is what I found:
H-Series H138 Elite miniLab ISFET pH Meter $357 + $31.00 freight. Replacement probe $79.60
ISFET is a microchip design, does not need to be kept wet, it's not as temperamental as the usual membrane/bulb types, it's auto-calibrating and temp-correcting, only tales a drop to calibrate or take a reading. Wipe it dry and store it. dry when done. Extremely convenient.
Hanna Checker Digital pH Meter HI 98103 $55.95
In spite of the advertising it can be very time consuming to calibrate and get a repeatable reading. It has a highly accurate probe with 0.01 pH resolution. Not suitable for field testing, only the occassional batch.
Hanna HI 98128 pHep®5 pH/Temperature Tester 0.01 pH resolution $112.50
This is one of the most common ph testers used. Overall, it worked well for me.
Extech PH100 ExStik pH Meter $84.99
resolution of 0.01pH and accuracy ±0.01pH.
tells you when it's time to replace your pH electrode.
the CAL feature tells you when it's time to recalibrate your meter.
a display indicates when the reading is stabilized.
The Extech PH100 is also available in a refillable model, the Extech PH110 pH meter, which features the same specifications as the PH100 but has a pH electrode that can be reused by refilling the reference solution once it is depleted. Refilling the electrode allows users to obtain continuously high accuracy by using fresh reference solution. The Extech PH110 pH meter also eliminates the concern of electrode shelf life.
Vinmetrica SC-300 Testing Unit (free sulphur, pH, TA) $355
Hands down, this is the most highly reccomended tester. There is also a model SC-200 available for ph only, but most everybody uses the SC-300.
My pick included the last two. The Extech PH100 for field use, and the Vinmetrica SC-300 for lab use. I should have splurged for the H138 Elite. Next time.
* Here is a tip to keep the ph meter probe moist. Instead of having to add storage solution monthly to the cap, put a few ounces in a narrow container. Insert the probe and cover with Saran wrap or similar and secure with a elastic band. Now you can see instantly if it needs solution added.