With the advent of aquariums and the use of more equipment on certain types of tanks, it is not uncommon to find that hobbyists are using pH monitoring or pH controlling equipment.

The variety and quality of these devices ranges from the very inexpensive pen-types to the real sophisticated laboratory type meters and controllers. Some units are made and sold by aquarium equipment manufacturers, yet others can be obtained from specialized companies that cater more specifically to the needs of the scientist.

If the hobbyist is going to rely on this type of equipment to monitor and adjust aquarium pH levels, it is certainly advisable to use a high quality instrument. Pen-type pH meters may be inexpensive but, unfortunately, they are not very reliable and may not give the hobbyist the accuracy level sought.

You could use them for a quick measurement to get a general idea of where your pH level is, but if you want to monitor it accurately and with enough significant digits, it is probably not the type of unit to use.

Regardless though of the unit itself that displays the pH value (and there are many brands of course of greatly varying prices) you will need to ensure that the electrode you use is measuring the pH accurately.

This involves calibrating the electrode and the unit to reflect the known pH of a solution you acquire or, better even, prepare each time you calibrate your meter or your controller.

For accuracy's sake it is better to prepare the solution that has a known pH each time you need one, calibrate and dispose of the solution. Since you have used it, it is contaminated and its pH has changed.

Some ready made solutions are marketed and they should ideally carry an expiry date. If they don't, you cannot be sure that the stated pH is actually still correct at the time you use it (chemical degradation and chemical reactions within the solution over time, alter its pH and make it unreliable if you want real high accuracy).

Powdered calibrating packages are, in my opinion, far better to use and more stable over time. Just take the powder in the packet and add it to the specified amount of water (usually distilled) and then slowly bring it to the right temperature (usually room). Your solution is now ready for immediate use in calibrating your electrode.

The suggested procedure is as follows:

1. Rinse the electrode in distilled water. Swirl it around in the vial you use
2. Clean the electrode with a mild acidic solution. Move the electrode around in that solution so dirt loosens. You can use 1 teaspoon of muriatic acid added to a quart of water
3. Rinse the electrode again with distilled water and move it around to dislodge dirt
4. Repeat the above steps a few times until the electrode is clean
5. Prepare your calibrating solutions (habitually you will need two, a low and a high)
6. Now follow the directions that come with the calibrating solutions and also the directions that came with the unit you are using that explain how to calibrate. Because instructions vary, this cannot be generalized
7. Often though the preparatory steps are left out of the instructions and those are the ones I find most useful and have listed here. Without the initial steps you may find that your electrode is actually dirty and that even though you calibrate and double calibrate as is often suggested, yet the readings you obtain in your tank are not accurate.

Should you calibrate often? The answer is difficult to give but the higher the load in the tank the more often I suggest you calibrate.

Keep in mind that with a high load, your electrode will foul more rapidly and will, as a result, have a tendency to give you erroneous pH readings.

Since pH control and stability are important in tanks, ensuring that you know what the pH is appears, indeed, to be important to me.

Meters and controllers purchased from reputable aquarium manufacturers or laboratory supply houses are of a much higher quality and precision. Anyone deciding to invest in such an instrument would be well advised to spend the extra dollars needed to purchase a unit that is both dependable and offers a high degree of accuracy and repeatability in measurements.

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