Keeping an eye on the most important water values

Professional water analysis – this sounds punishingly expensive. It makes you think of a laboratory which sends you back a record sheet with results which you don’t know how to use, as with your blood values. But the professional water testing in your aquarium or pond at home also works on a high level and above all it is simple and inexpensive. Also on the Expéditions JBL Test d'eau are used and have reliably delivered the water values of many biotopes on earth.

In each test case and each individual test you will find references in the instructions and the water analysis sheet to the correct value ranges of the parameters for their intended purpose. In addition you receive recommendations for action which will lead to solutions, if the measured values are outside the recommended range. We distinguish here between the conventional community aquarium with fish; a plant aquarium (also called scape) with no or only a few fish; a marine aquarium; and a garden pond.

Base measurements –carry out always

In the aquarium there are four parameters which you should regularly monitor. In addition you should note the date and time of each measurement. Only then can later changes be recognised and in case of problems can appropriate measures be taken.

The following table shows you the 4 most important parameters with the ideal target values in the respective water type:

freshwater with fish freshwater without / few fish (ProScape) Bassin seawater
date / time:
temperature (°C) 23 - 28 23 - 26 4 - 25 24 - 28
KH carbonate hardness (°dKH) 5 - 12 3 - 8 4 - 12 7 - 10
pH acidity 6.5 - 7.5 6.0 - 7.0 7.5 - 8.5 7.9 - 8.5
GH general hardness (°dGH) 8 - 25 3 - 10 6 - 20 - - -

Fish mortality – common causes

If several fish die all at once it cannot be assumed that it is a normal death. If there are no noticeable symptoms of disease bad water values are often the cause. In that case the base measurements need to be carried out and to be completed with four further parameters:

freshwater with fish freshwater without / few fish (ProScape) Bassin seawater
NH4 ammonium (mg/l) < 0.25 < 0.25 < 0.1 0 - 0.25
NO2 nitrite (mg/l) 0 - 0.2 0 - 0.2 0 - 0.2 0 - 0.2
Cu copper (mg/l) 0 - 0.3* 0 - 0.3* 0 - 0.3
O2 oxygen (mg/l) 5 - 8 5 - 10 5 - 20 5 - 10

Problems with algae or plant growth

Everyone has experienced this at some time or another. The plants don’t grow as expected or the aquarium has an algae problem. Assuming the plants have been given the necessary technical environment (light and CO2), these two symptoms are a result of the water values. In the following posts we have already reported in detail about plant growth and the most important step to perfect growth:

1. Fertilization is not just fertilization Part 1

2. There’s more to fertilization than you’d think Part 2

3. Why is carbon dioxide (CO2) the most important plant nutrient in the aquarium?

4. Water values for water plants in detail

If plants don’t grow well algae problems are not far away. Below we have compiled eight measurable factors with target values to help you find the root cause of the problem. An imbalance of these values leads to the problems described. If you manage to return the values into the right range improvements will usually show after 2-3 weeks without having used an anti-algae agent. We only advise the supporting use of an anti-algae agent when the algae is so bad that the plants have no other means of recovery. But the water values still need to be brought within the normal range to achieve long-term success.

freshwater with fish freshwater without / few fish (ProScape) Bassin seawater
conductivity 150 - 800 μS/cm 150 - 600 μS/cm 250 - 800 μS/cm 49 - 52 mS/cm
NO3 nitrate (mg/l) 0 - 50 10 - 30 0 -10 0 - 20
PO4 phosphate (mg/l) 0 - 0.4 0.1 - 1.5 < 0.05 0 - 0.1
SiO2 silicate (mg/l) 0 - 2.0 0 - 2.0 0 - 2.0 0 - 1.0
Fe iron (mg/l) 0.05 - 0.2 0.1 - 0.5 0.05 - 0.1 0.002 - 0.05
K potassium (mg/l) 10 - 30 10 - 30 - - - - - -
Mg magnesium (mg/l) 5 - 10 5 - 10 - - - - - -
CO2 carbon dioxide (mg/l) 15 - 35 20 - 35 - - - 0.04 - 2.5

Seawater special – coral growth and health

The classifications above also apply in the marine aquarium. The base measurements are reduced by the general hardness (GH) parameter. Three parameters have been added and as they are new water values they need to be checked during each test run,

Ca calcium (mg/l) 400 - 440
Mg magnesium (mg/l) 1200 - 1600
salinity at 25°C 1.022 - 1.024

CO2 calculation

You can calculate the CO2 content without measuring it. First measure the carbonate hardness and the pH value. Then look in the adjacent table for the row and column with the measured carbonate hardness and pH value. At the intersection point of the corresponding row and column you will find the value of the CO2 content. The area with sufficient CO2 content for ideal plant growth and pH value without an adverse effect on the fish is coloured clearly.

Recommendations for action – increasing or decreasing values

The proper documentation of the water values will help you to recognise the problems and to intervene in good time. For this purpose we have prepared a water analysis sheet for you to download. Aquariophilie professionnelle avec JBL

On the back you will find additional recommendations for action in case a water value requires an increase or decrease. Those who rather want to check the water values by computer instead of on paper can use the Laboratoire en ligne pour analyse d'eau for analysis purposes with an evaluation and instructions.

© 18.09.2016
Matthias Wiesensee
Matthias Wiesensee
M.Sc. Wirtschaftsinformatik
JBL GmbH & Co. KG

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