andysworld!

The secret of breeding and keeping fish is all about managing water, and to successfully manage water you need to understand a little water chemistry.

pH
pH is the measure of acidity or alkalinity of water. A pH reading of 7.0 is neutral. A pH higher than 7.0 is alkaline, and a pH lower than 7.0 is acidic.

pH is defined as follows: the lower-case letter “p” in pH stands for the negative common (base ten) logarithm, while the upper-case letter “H” stands for the element hydrogen. Thus, pH is a logarithmic measurement of the number of moles of hydrogen ions (H+) per liter of solution. Incidentally, the “p” prefix is also used with other types of chemical measurements where a logarithmic scale is desired, pCO2 (Carbon Dioxide) and pO2 (Oxygen) being two such examples.

In layman’s terms this means, that a 0.2 change in pH is a big change to fish, never try to change the pH of aquarium water by more than 0.2 a day.

I use an Aquarium test kit, manufacturered by Aquarium Pharmaceuticals Inc to test for pH. This is a wet kit, but there are many different test kits around, and some dry kits which are quicker to use, but more expensive. I also use digital pH testers for quickness, but the pH probe has a life, and must be regularly calibrated before use.

pH should be tested weekly, since natural materials in the aquarium can cause a pH change.

KH
K(c)arbonate hardness is the measure of carbonate and bicarbonate ion concentrations dissolved in water. These minerals are present in our tap, well and bottled spring water. The level of carbonate hardness in tap and bottled water depends on the source of the water and the treatment process it has undergone. Carbonate hardness helps stabilize pH in the aquarium. An aquarium with a very low KH < 50ppm will tend to be acidic. Aquariums with a very low KH level are subject to rapid pH shifts, if not monitored carefully, sometimes referred to a pH crash. Water with a high KH level > 200pm usually have a high pH. KH is usually measured in dKH.

GH
General Hardness is the measure of calcium and magnesium ion concentrations dissolved in water. These minerals are also present in in our tap, well and bottled spring water. It also depends on the source of the water and the treatment process it has undergone. Hard water > 200ppm is high in calcium and magnesium, while soft water 50 – 100ppm is low in these minerals. GH is usually measured in dGH.

To convert both GH and KH to parts per million (ppm) multiply by 17.9.

I use a test kit manufactuered by Aquarium Pharmaceuticals Inc to test for KH & GH.

Why am I telling you all this? Over the forthcoming weeks, I’ll be installing a Dennerle CO2 system into my display tank to aid plant growth, and I’ll be using terms such as pH, KH and GH, so you’ll understand what I referring to!