Reef Central - UK

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At Seachem, we get many questions from hobbyists, not all directly related to our product line. We do our best to be helpful and answer questions without bias. We do not, however, follow the crowd, so that sometimes our views may seem contrarian. Here are some of the issues that come up repeatedly.

The most frequently recommended practice for reef maintenance is the addition of limewater or calcium hydroxide solution either in a continuous drip or when replacing water of evaporation.

Redox is another poorly understood measurement in the hobby. Redox is measured with an electrode, very much like pH is measured with an electrode. Just as electrode pH measurements are very much dependent on a properly functioning and calibrated electrode, true redox measurements are even more dependent on function and calibration of the electrode. Unfortunately, redox calibrators do not have the stability characteristic of pH calibrators. While accuracy and precision are dependent on electrode function, many hobbyists have the natural inclination to assume that digital read-outs are highly accurate, regardless of the condition of the electrode.

pH is generally understood to be an expression of acidity or the hydrogen ion (H⁺) concentration in water. The value is a negative logarithm, which means that acidity increases as the value decreases and that each unit change reflects a 10-fold change. Although not totally correct, this concept serves us well and is not difficult to comprehend. In considering pH and pH control in the marine environment, however, the inadequacies of this concept have caused some fundamental misreasoning. pH is what the pH meter reads: a negative logarithmic expression of the hydronium ion concentration (or hydrogen ion activity).