View Full Version : Ph meter

09-15-2007, 09:31 AM
I finally broke down and bought a Ph meter (the yellow/green strips were diriving me nuts......short drive).
It's a hanna checker one, which I seem to remember reading about here. $39 for the meter, 4 packs of 7.01 solution and 3 packs 4.01 solution shipped to the door in two days. They did say that electrodes are not long lived, 6-12 months more or less, but replacements were in the $17 range. The short electrode life was my big gripe, but I was unhappy with the strips.

09-15-2007, 09:44 AM
You can extend the life of your probe by always storing it in a probe storage solution. You should be able to get some from the same place you got your meter and calibration solution.

BTW, I have a higher-end meter, and I calibrate mine before every use.

09-15-2007, 11:24 AM
From my experience working in a chemical lab (years ago)... don't EVER let the probe tip dry out. Always store it in a neutral buffer solution. If you can't find any probe tip solution, then make your own out of distilled water and baking soda. The single biggest cause if premature tip failure in these meters is due to dried electrolytes "gumming up" the junction in the tip. You keep that from happening by keeping a ready source of balanced charges happily circulating around the tip.

Of course, Luddite that I am, I still use pH strips in the meadroom... but fortunately BD is gonna sell me his old meter, so I'll thereby enter the world of "high tech" meadmaking!! :sign13:

09-15-2007, 09:35 PM
The Ph meters I have worked with recommend storing the probe in a salt water solution when not in use. If the probe does dry out you can rehydrate it but it will need to be calibrated.

09-15-2007, 10:29 PM
The saline solution works the same way. The idea is to have a good dose of positive and negative ions in solution, which helps with electron motility across the junction of the detector. Rehydrating the probe tips after they dry will sometimes work, but sensitivity is lost, and in the worst case they just stop working all together.

CORRECTION: My memory isn't what it used to be, so I checked my old documentation and found that the storage solution isn't an alkaline buffer; rather it is a weak acid. The acid is used to replenish hydrogen ions that are depleted from the probe tip when it is used in measurement, and also to keep a semi-permeable portion of the tip "wetted" to facilitate the migration of the solution under test into the probe where the actual measurement takes place. Traditionally the acid used was either HCl or KCl, or a mixture of both.

Sorry for the "memory bit slip" in my earlier posting.

09-16-2007, 03:27 PM
Avoid drying the electrode at all costs - in most cases it will kill it. Also - never store pH electrodes in DI or RO water. There are special storing solutions, that you can use for pH electrodes, but about 1M KCl solution will do as well, or any of the the buffers used for calibration (pH 7 preferred). If you are completely out of any solutions, add three teaspoons of a kitchen salt to the glass of tap water - it will be much better that nothing.

09-16-2007, 08:29 PM
Hanna recomended their own 7.01 solution for storage in the tip cap. I am happy to get the impression from folks here that longer life is possible. Drying out was warned against as well as not using plain water in the tip cap. I didn't get a chance to fire her up yet. The tip cap looks like it has a dry crystalline goop around its opening which I'm assuming I should clean off.

09-16-2007, 10:58 PM
Gently rinse the crystals off with a slow stream of tap water before taking the tip cover off and you'll be fine.