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eSHa Aqua Quick Test


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With eSHa Aqua-Quick-Test you can monitor five values which are crucial for good water quality: pH (acidity), KH (carbonate hardness), GH (general hardness), nitrite (N02) and nitrate (N03). It is important for you to understand what can cause abnormal values and what action you can take if the test strip indicates that the water quality is not good.

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Water quality is the result of many factors. The most important factors are: plants, fish, aquarium volume, bottom layer of sediment etc. as well as external factors such as overfeeding, type of water added, the filter used, acid rain, duration and amount of lighting, sunlight etc. Rarely is there a stable and completely natural balanced system. aquaria and ponds are set up by people whom also choose the plants and fish. The system has not developed naturally. some plants and fish are very adaptable. Others are more sensitive to their environment and need a very stable and optimal water quality. Therefore, you sometimes need to give your aquarium or pond a helping hand.

Acidity or pH of the water. pH is measured on a scale of 0 to 14. a value of 7 is neutral. If the pH is lower than 7 then the water is acidic. If the pH is higher than 7 the water is alkaline. The pH in aquaria and ponds normally fluctuates during the day/night cycle. These changes in pH are caused by changes in CO2 (carbon dioxide) concentration (due to plant growth). During daylight hours the pH rises only to fall back to its original value during the night.

eSHa pH

The pH is very important for all living organisms in aquaria and ponds. Its importance is increased even more due to the way pH influences and interacts with other factors. For example:
- the KH determines how easily the pH can change. A low level of KH allows the pH to fluctuate more quickly and over a wider range.
-higher pH values cause harmless ammonium (NH4+) to change into harmful ammonia (NH3).
-if your pH is over 7.8 check your ammonia levels regularly using an ammonia test kit.

Adjusting the pH should always be done gradually; a quick increase or decrease is harmful.
Favourable pH value for household aquaria: 6.8 to 7.5
Favourable pH value for ponds: 7.0 to 8.0.

Adjusting the pH. Lower the pH with peat products, soft water or eSHa pH-min. Raise the pH by adding hard water or eSHa KH-plus. Acid forming or alkaline materials should be removed if present.

Measurement: Compare the colour of the test strip with the reference colour chart. If the colour of the test strip is in between two reference colours, the pH value is also intermediate. A test colour between 7.2 and 7.6 indicates a pH of 7.4 (higher or lower depending on colour intensity).

eSHa stick

pH inaccuracies in low KH conditions: The accuracy of the pH test can be affected in low KH conditions (low buffering capacity). This is because of the levels of pH determining components (acid and alkaline) are not present in sufficient quantities for the pH test to register accurately. If KH registers at 4odH or lower the pH test may not be accurate. however, all the other tests on the strip remain accurate. Low KH can result in major pH fluctuations which can be life threatening for aquarium fish. Therefore, a KH of 4odH or higher is recommended. tap water of 4odH or lower is uncommon in most areas.

Water Hardness. For aquaria and ponds both general hardness and carbonate hardness are important. From a biological point of view, general hardness is the most important. Within certain limits, fish and plants can adapt to changes in GH. Carbonate hardness (KH) is very important biochemically; it has a direct influence on pH and CO2.
GH-General Hardness: GH is the sum of all the substances dissolved in water which determine the hardness or softness of the water. (These are salts of calcium and magnesium such as sulphates, carbonates, chlorides etc.)

GH is what is meant when fish or plants are said to prefer hard or soft water. The reason for this is that GH influences cell membranes, kidney function, growth, transport of essential salts, incorporation of minerals and trace elements, osmotic pressure, etc. Be careful with materials (such as decorative rocks) which release calcium and magnesium salts into the water. They make the water hard and keep it that way. Adding a lot of tap water or rain water or replacing part of the water often changes the GH value.

Favourable values in household aquaria are 6o to 12o GH and in garden ponds 7o to 14o GH.
If too low; add hard water or eSHa GH-Plus. If too high: dilute with soft water, use ion exchange filter or absoption filter.


none of the Gh test squares are purple
one of three GH test squares purple
two of three GH test squares purple
three of Gh test squares purple

GH lower than 6
GH more than 7
GH more than 14
GH more than 21

A test square that is partially coloured indicates an intermediate value. One fully coloured square plus a second square that is faintly or partially coloured indicates a GH of about 10. Also see conversion table.

KH-Carbonate Hardness (Buffering Capacity)
KH contributes to the general hardness of water and is made up of salts of carbonate and bicarbonate. Because of its ability to bind acids in water, KH is responsible for the buffering capacity of water with respect to acids. Important: KH has a direct influence on the acidity on the carbon dioxide concentration which is also important for plants. The KH level tends to decrease with time due to biological processes which remove calcium carbonate from ater. If the KH level falls to 4o KH or lower, the plant and animal community in the aquarium will begin to suffer. Too little KH leads to erratic and unstable pH values which is harmful. Tip: In newly established ponds the KH value is often too low. Good (buffer) values for household aquaria are 4o to 10o KH and in ponds 6o to 12o KH.

KH values which are too low or too high can cause problems with plants and fish.

If KH is too low
If KH is too high

add hard water or eSHa KH-plus
add soft water, filter over peat or other products which lower KH

Compare the colour of the KH test square with the reference colour chart on the tube. A test square that is partially coloured indicates an intermediate value. A colour between 10 and 15 for example means a KH value of 12 to 13. also see the conversion table. (less or more depending on the colour intensity.)

Recycling of Waste Products or Biological Stability
In nature, biological waste products of fishes and plants including dead plant fragments and food remains are broken down and recycled. basically it's like a compost heap in which micro-organisms break down waste products. The compost which is the end result can again be used as a nutrient for plants. In the aquarium, waste products and their intermediates are first converted into nitrite which is finally converted into nitrate. This conversion is carried out by various kinds of micro-organisms. The level of nitrite and nitrate tells us something about the level of bacterial activity.
They tell us whether the various steps in the biological cycle are working properly, and as a result whether you have a well balanced aquarium or pond in which plants and fish will grow well.

Nitrite is produced when certain micro-organisms (nitrifying bacteria) break down waste products produced by fish, food remains, etc. nitrite is toxic for fish. Other kinds of bacteria are able to convert nitrite into the much less harmful nitrate. By measuring the level of NO2 we can actually check to see if there are enough 'good bacteria' present to convert the NO2 into NO3 just as quickly as the NO2 is formed. These good bacteria are mostly found in the filter and substrate and are sensitive to changes in acidity and low oxygen levels and especially sensitive to antibiotics and toxic substances. A high NO2 level means that the bacterial community is not functioning well. NO2 is less harmful in harder water.Favourable NO2 level is less than 0.3 mg/l.

If NO2 level is too high, quickly change the water. After changing the water, again measure the NO2. Try to discover the cause and add nitrifying bacteria if possible. Nitrifying bacteria reproduce, grow and recover slowly.

Cause of high NO2 levels:

  • too much waste material present
  • overfeeding
  • dead fish
  • not enough nitrifying bacteria
  • sudden changes in pH
  • antibiotics
  • unsuitable filter or filter material
  • not enough oxygen in the water
  • newly installed aquarium or pond

Compare the colour of the NO2 test square with the reference colour chart. A pink colouring of the test square means that NO2 is too high. Depending on the water's own natural colour, this indicates a value of 0.3 to 0.5 mg/l. If the colour is more intense than 0.5 mg/l action should be taken.

The last step in the process of breaking down waste is the production of nitrate by the micro-organisms.Within certain limits nitrate is not harmful to fish and is an excellent nutrient for non-aquatic plants. Aquatic plants use nitrate only in small amounts, however, algae thrive on it. Usually, in aquaria and ponds, more nitrate is produced than can be taken up by water plants. The simplest solution is to regularly replace the water before the nitrate level rises too much:

In aquaria:
In ponds:

replace a minimum of 20 to 25% per month
at temperatures above 15 oC, 10 to 20% per month

Favourable levels: preferably under 25 mg/l (to limit algae growth). For fish, levels between 50 and 100 mg/l are acceptable. at higher levels problems will occur in the long term. the best remedy is regularly replacing the water. (Tap water often contains high levels of nitrate. Test your tap water regularly for nitrate. The nitrate level can vary quite a bit from day to day, depending upon which pumping station is supplying your area with tap water.) Causes of high levels include: too many fish, not enough plants or unhealthy plants, not changing water often enough, poor conditions for nitrifying bacteria (if levels too high replace water). Remedy by adding more plants, have less fish, do not overfeed, filter over materials which will absorb nitrate.

Compare the colour of the test square with the reference colour chart. An intermediate colour on an NO3 test square indicate an intermediate value. A colour between 10 and 25 means that NO3 is around 20 mg/l (less or more depending upon colour intensity).
Acceptable Values



Garden Pond



6.8 - 7.6

7 - 8

Carbonate hardness


4.0 - 10 odH

6 - 12 odH

General hardness


6.0 - 12 odH

7 -14 odH



<0.3 mg/l

<0.3 mg/l



25 - 100 mg/l

25 - 100 mg/l


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eSHa Aqua Quick Test

eSHa Aqua Quick Test

With eSHa Aqua-Quick-Test you can monitor five values which are crucial for good water quality: pH (acidity), KH (carbonate hardness), GH (general hardness), nitrite (N02) and nitrate (N03). It is important for you to understand what can cause abnormal values and what action you can take if the test strip indicates that the water quality is not good.