WHAT IS pH
The pH value of water is a measurement of the hydrogen ion concentration. The results of a pH test can determine if the sample is acid (measurements between 0 and 6.99), alkaline or basic (measurements between 7.01 and 14.0) or neutral with a pH of 7.00.

pH ADJUSTMENTS
One of the most important aspects of dealing with pH is to note that adjustments to it are not relative. For example, to raise the pH of 20L of water from 5.0 to 6.0 may take only 100mg of a pH raising solution, but to raise the pH from 6.0 to 7.0 may take 500mg of the same pH raising solution. This factor catches many people off guard. They consider it took one spoon to adjust the pH halfway to where they wanted it, but when another spoon is added the pH does not go near their desired end point. Of course, going the other way and lowering the pH with acid the reverse would apply. An example is: o.5ml of an acid is used to lower the pH of an aquarium from 7.0 to 6.5 but another 0.5ml of the same acid takes the pH of the aquarium to 5.0.

Technically, logarithms may be used to define the hydrogen ion concentration and this may be expressed in grams per litre.

The quantity of a substance used to adjust or influence the pH value of a sample of water is dependent on the pH of the adjusting substance and the present pH of the water to be adjusted.

CHANGING pH
Many factors cause pH to constantly change in an aquarium. Organic matter and fish waste breaking down under biological filtration is an acidifying process and so causes the pH to become acid. The influences of calcium and magnesium in the form of shells, coral or other calcite material tends to make the pH of water, containing such things, alkaline.

pH IN THE NATURAL STATE.
Just as influences in an aquarium affect the pH of its water, so in the natural state, geographical location and vegetation can alter the almost neutral pH value of rain water as it leaches through decaying leaf matter or runs over limestone deposits. This has left many species that naturally inhabited a stream to develop pH preferences. Some fish even wait for a pH change to breed, as would happen with a flush of new rain water abruptly altering their habitat.

CARBON DIOXIDE INFLUENCE.
For the pH to read without carbon dioxide influence, carbon dioxide has to be in equilibrium with the atmosphere. If the carbon dioxide content of a sample of water is less than in the atmosphere then the pH will read higher. If the carbon dioxide content is more than the pH will read lower.

WAYS OF SETTING AND DEALING WITH pH
There are many ways of stabilising, setting or adjusting the pH of an aquarium to a desired point. In each case, to reach the desired point, other opposing influences may have to be overcome. For instance, it is very difficult to stop an aquarium from going alkaline ( and uncontrollably hard) when the gravel contains quantities of shell-grit or other calcite material.

Traditional methods of dealing with pH have been applied in different locations according to shopkeeper knowledge, preferences and local water conditions. Basically, locations may be divided into two areas. (A) Hard water areas. (Hardness above 150ppm) and (B) Soft water areas (Hardness below 150ppm).

HARD WATER LOCATIONS
In some of these areas water is excessively hard and the biggest problem is lowering the pH and keeping it down. Pre-filtering the tap water through ion exchange reains will remove the hardness. If this is not available AQUASONIC pH-LOWER (See below) will lower the pH successfully.

SOFT WATER LOCATIONS
In these areas it is recommended to add AQUASONIC "NATURAL HOME" WATER CONDITIONERS (according to the fish species kept) to raise hardness and help control pH better.

pH CONTROL IN THE AQUARIUM

AQUASONIC NEUTRALISING BLOCK.
A simple and easy method to control acidity. As acids are produced, calcium is leached from the blocks forming carbonates and bicarbonates which in turn neutralise the acids. This method will cause the water to become harder, so regular water changes or testing of hardness is necessary.

AQUASONIC Neutraliser Blocks not only neutralise acid aquarium water, they contain Vitamin B1, an important vitamin to help guard against infection and stimulate breeding. Each block takes 10 - 14 days to dissolve.

pH - UP AND pH - DOWN.
These products supply, in a pure form, the chemicals sodium bicarbonate and sodium biphosphate for raising and lowering the pH. This method is the most widely used biphosphate for raising and lowering the pH. This method is the most widely used by hobbyists for adjusting pH to a desired level. It is normal for aquariums to go acid (see previous page), so, dependent on stock load, regular pH testing (at leas once a week) adjusting with pH-UP will be necessary.

If the pH of an aquarium continually turns alkaline after adjustment with pH-DOWN then usually a calcite substance will be present, most likely shell-grit, in the gravel. As stated previously, this will make the water harder as well. Replacement with non-calcite gravel is the best option.

kH GENERATOR TABLETS AND pH-LOWER
This is the preferred way to set a pH. The advantages are (A) a very stable and continuous pH value (B) an alternative source of a carbon dioxide supply for aquarium plants (C) no effect on water hardness (no Calcium).

To use this method, the carbonate hardness is raised using AQUASONIC "kH-UP" CARBONATE HARDNESS GENERATOR tablets. The carbonate hardness should only be raised at the rate of 20ppm per day and one kH-UP tablet will raise the carbonate hardness of 120 litres of water by this amount.

As the carbonate hardness rises, so too may the pH. This is then lowered with AQUASONIC "pH-LOWER". In this process a buffer is formed which sets and stabilises the pH. This stability of pH will last many weeks even in heavily stocked aquariums and even if no further maintenance to the carbonate hardness reserve is undertaken.

NOTE: Adjusting pH does not preclude the necessity of regular water changes.

CARBON DIOXIDE GAS INFUSION
The pH of water with a solid carbonate hardness reserve may also be controlled by infusing carbon dioxide gas into the water. This method is an aid to plant growth. wet-up costs may be prohibitive for some hobbyists.

WHAT MAKES A GOOD pH TEST KIT?
The method used to test pH in an AQUASONIC TEST KIT is different to most others. Although the reagent for testing (Bromothymol blue) is commonly used in fresh pH test kits, the Aquasonic one is itself pH adjusted. It is also made with glass distilled water, greatly increasing shelf life. It is up to 4 times stronger than most of its competitors and so goes 4 times as far. The method of test is also a little different, a large quantity of water is used in the test greatly reducing the risk of influence from previous tests and the indicator itself. To view a test, look down vertically through the tube on the colour chart for a most accurate pH test.

Published by AQUASONIC