What is pH?

pH stands for the ‘potential of Hydrogen’. pH values define whether water is neutral, acidic or basic (alkaline). This is accomplished with a pH scale that ranges from 0 to 14.0. pH represents the concentration of Hydrogen ions [H+] in a liquid solution. The 0 to 14.0 scale measures the proportion of positively charged Hydrogen ions [H+] versus the existing negative Hydroxyl ions [OH-].
Neutral water has a pH value of 7.0 (an equal value of [H+] and [OH-] ions). Acidic values fall below neutral, under 7.0 to 0 (a higher concentration of [H+] ions), while alkaline values are above neutral, over 7.0 to 14.0 (a higher concentration of [OH-] ions).
Example: An acid contains positively charged ions [H+]. In a scenario where the pH of aquarium water is too high, the introduction of an acid will drive the pH down.


The pH scale

The pH scale is logarithmic. For example, a pH of 6.0 is ten times more acid than a pH of 7.0 and one hundred times more acid than a pH of 8.0. It is important not to effect changes of pH in excess of 0.5 per 24 hour period, to reduce stress and shock reactions in fish.

Hydrogen ions [H+] Hydroxyl ions [OH-]



Fish and Ideal
pH Ranges


In general, many species of fish are found in waters with ranges of pH from 6.0 to 8.0. For general well-being, it is even more important that pH levels are constant, with minor fluctuations permissible.

If fish are kept at pH levels significantly out of their preferred range, or if exposed to rapid changes, they may exhibit symptoms such as gasping, erratic swimming, mucus secretions (appearing as whitish slime), fin damage and reddish sections of the body.
    

The following groups of fish generally prefer the listed pH ranges. Respecting the indicated ranges will help provide a guideline for optimal conditions and for mixing species with common water condition preferences.
  Livebearers:
7.0 to 7.6
  African Cichlids:
7.8 to 8.5
  South American
Cichlids:
6.2 to 6.8
  Tetras:
6.2 to 6.8
  Rasboras:
6.2 to 6.8
  Rainbows:
7.0 to 7.4
  South
American Catfish
(Corydoras, etc.):
6.2 to 6.8
  Goldfish & Koi:
7.0 to 7.5


Carbonate Hardness (KH)

What is Carbonate Hardness?
Carbonate Hardness measures the capacity of water to neutralize an acid, also known as buffering capacity. Carbonate Hardness, often referred to as alkalinity, is predominately composed of bicarbonate ions  (HCO3-)  and carbonate ions (CO3- ) within a pH range of 6 to 8.2. Carbonate Hardness can be understood as temporary hardness, in that its reserve is diminished as acids are neutralized.
Carbonate Hardness (KH)

Why is Carbonate Hardness Important?
Carbonate Hardness stabilizes pH. This vital chemical parameter should be kept constant. Furthermore, it is a source of energy for nitrifying bacteria and an important carbon source for aquatic plants (especially hard water plants). Carbon dioxide levels in aquariums are often deficient and bicarbonates can represent an alternative carbon source for plants.



How to adjust?

How to Adjust Carbonate Hardness:
It is suggested to determine the appropriate level of Carbonate Hardness for the aquatic life being kept. As a general guide, most fish and plants should be maintained at 50 to 120 mg/L of Carbonate Hardness. African Cichlids enjoy higher levels, and should be maintained from 120 to 280 mg/L of Carbonate Hardness. Proper KH levels will ensure pH stability and provide an energy source for plants and nitrifying bacteria.

Should it be necessary to lower Carbonate Hardness, Fluval Granulated Peat may be used. Peat is an effective media for lowering Carbonate Hardness and pH. To increase Carbonate Hardness, pH Stabilizer should be used. Raise at a rate of 20 mg/L per day (maximum rate if fish and plants are present) until the desired level is obtained.

The ingredients in pH Stabilizer will have minimal effect on pH and contain beneficial compounds for plants. Always use the Hagen GH/KH test kit after each dosage to measure existing levels.


pH stability

How to Maintain pH stability:
Because of natural biological processes that exist in the aquarium, acids are produced and the pH can be affected. The direct relationship that exists between buffering capacity and pH is very important to ensure that fish, plants and essential biological processes enjoy a natural, stress-free environment.
Therefore, not only should we strive to maintain stable pH through regular testing, proper maintenance and deploying effective products such as pH Adjust é or ę, but through the understanding of the source of pH stability, which is buffering capacity.



Aquarium Test for Fresh Water



Why is pH important?

With respect to its role in the blood system of aquatic organisms, pH is one of the most important chemical parameters. It should be verified on a regular basis to maintain the appropriate aquatic environment for the types of fish and plants that hobbyists keep.

Color, behavior and reproduction of fish are affected by pH. It is therefore a vital element for the control of optimal aquarium conditions. Plants usually tolerate fairly wide pH ranges, however, many species prefer slightly acidic to neutral water. Providing plants with proper pH levels will help them to out-compete algae.


Medications for freshwater fish can be affected by pH and water hardness. Treatments for fish containing copper should be carefully monitored when being administered in soft water.


Stability is important with respect to pH values. Fluctuations of more than 0.5 can be very stressful. Fluctuating pH levels in the aquarium can indicate poor buffering capacity.
In this case, the KH (carbonate hardness) should be verified and corrected by using Hagen pH Stabilizer until the desired KH value is obtained (ideally verified with a Hagen KH Test Kit).


When acclimating new specimens, care should be taken to ensure that changes in temperature and pH are effected gradually. Therefore, before acclimation starts, temperature and pH should be verified and longer periods of acclimation should be allowed when significant differences exist.
pH is an important factor with respect to ammonia (made up of toxic ammonia (NH3) and ammonium (NH4).   The balance that exists between NH3 and NH4   is  dependent on temperature and the pH of water. As pH increases, the toxic form of ammonia (NH3) also increases. In this situation, the gradual use of pH Adjust ę can help reduce the stress and danger associated with ammonia.

pH levels also affect nitrification by beneficial bacteria. At pH values below 6.0, nitrifying bacteria are less active. This can negatively affect the existing biological filter.
When performing partial water changes, one of the most important activities in proper aquarium maintenance, it is recommended to test the existing aquarium pH and that of the replacement water.
An assortment of Hagen pH Test Kits exist for this purpose. The pH of tap water can vary with respect to seasons and other factors. If the values differ by more than 0.2, it is recommended to equalize the two values by using pH Adjust é or ę.

If performing a water change due to an ammonia presence, ensure that the replacement water is of the same pH or less (avoid differences of more than 0.5) to eliminate increases in the quantity of toxic ammonia.



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