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If you own a pool, there is no way around dealing with the technology and especially the water quality for lasting bathing fun. Despite enough chlorine and a regulated technique, it can still happen that the pool water turns green. What went wrong in this case and what a remedy promises is explained in an easy-to-understand manner below.
Why does pool water turn green?
It is actually assumed that a pool using chlorine and with the presence of a filter system is not critical and that the water quality is always in the "green" range with regular checks and readjustments. However, there are various aspects that can cause problems for a system that is consistent in itself. The result is usually the formation of algae, which then leads to the undesirable green coloration of the water:
- Wrong PH value, which encourages algae growth and reduces the effectiveness of the chlorine
- High dirt entry, thus increased nutrient supply for algae
- Disturbance or failure of the filter, resulting in a high content of foreign matter and nutrients in the water
danger: Pool water turning green is often associated with the appearance of algae. Of course, the connection of aquatic life with coloring is correct. However, there are always small amounts of algae in the pool water. However, it is only when they multiply excessively that they lead to clouding of the water and finally discoloration!
Eliminate green pool water
Once it has gotten to the point that the actually clear, inviting water of the pool has degenerated into a cloudy and unappetizing green soup, the causes must be tackled in a targeted manner. It is worth proceeding in several stages:
- Direct combat of algae to prevent further proliferation
- Elimination of the causes of the immense growth of algae
- Adjustment of the water values for a functioning disinfection
You can find out how to implement the individual steps in the following step-by-step explanations:
Phase 1 - Curb algae growth
Although you can't get the actual problems under control by fighting the algae, you can prevent further proliferation and thus an intensification of the green pool water quickly and easily. Ideally suited is the use of so-called algicides, i.e. agents specifically developed to kill algae:
- Determine the pool volume, either already known, or to be calculated using length x width x height
- Determine the amount of algaecide required from the tank volume and the manufacturer's information
- Add the agent to the pool water according to the manufacturer's instructions and observe the specified waiting time, if necessary activate circulation to improve distribution or set the water in motion manually
Phase 2 - elimination of the cause
After the immediate proliferation of the unwanted pool dwellers has been prevented, it is imperative to subsequently eliminate the cause that enabled the algae to grow to the extent encountered. Of course, the first step is to determine the cause. For the sake of simplicity, the search for the cause is dealt with directly with the respective remedy.
Wrong PH value
- Determination of the cause via pH test set, pH test strips or laboratory test
- Defining a target pH value (ideally between 7.0 and 7.4) and comparing the actual value with the target value
- Determination of the required pH value reduction or increase
- Selection of suitable preparations for pH value adjustment via suppliers of pool supplies
- Depending on the preparation selected, dosing according to the manufacturer's instructions and the pool content already determined for combating algae
- Adding the preparation to the pool water and ensuring an even distribution
- Finally, check the pH value again as already described
danger: In the further course of the algae control, it is possible that the pH value of the water changes again due to renewed additions of chlorine and other activities. It should therefore be checked again before resuming bathing operations to ensure that the water disinfection is working properly using the chlorine present!
High dirt entry
- Fish off floating foreign matter by using a pool net
- Removal of sunken dirt particles by activating the water circulation and using existing filter devices
- Remove adherent debris from the pool floor and walls by using a pool brush
notice: In addition to the dirt particles brought in from outside, the foreign matter to be removed naturally also includes the algae that have been killed in the meantime. As a mostly firmly adhering coating on the pool surface, the dead algae represent an ideal biofilm and thus a breeding ground for future algae growth.
Water filtration failure
If there are problems with the filter system of the pool, the most difficult thing is to rectify the cause. Depending on the type of system, very individual steps may be required. In general, however, this procedure is effective in most cases:
- Testing of the general function, usually recognizable by a control lamp or by operating noise
- Missing function: first check the power supply, check the fuse if there is one, check the plug connections for tightness and check the ballast and cables for damage - don't forget the power supply at the house!
- General function noted: check the output of filtered water
- If there is no water output, open the filter and check for foreign matter, either remove the filter and clean it, or replace the filter material
- Check the supply line to the filter for foreign bodies
- If it still doesn't work, consult a competent technician
danger: As a layperson, you should never open electrical or mechanical components of the filter system that are not intended for this purpose. As a result, the components could be damaged and injuries caused. Intensive work on the filter system should therefore only be carried out by competent persons, such as the manufacturer's service technicians!
Phase 3 - Establishing the water balance
Once all active work to eliminate the algae infestation has been completed, restoring the desired water balance helps to actively prevent renewed infestation. The steps may be particularly necessary if part or even all of the water in the pool has been renewed due to heavy soiling. This measure can be useful after a heavy algae infestation, as despite cleaning and filtration, cloudy substances can still remain in the water, which can only be completely removed with great effort. Essential steps for adjusting the water values are:
- Check the pH as already described
- If there are deviations from the ideal value, the pH value can be readjusted using a pH reducer or raiser
- Chlorine level control
- Addition of chlorine if the chlorine value is too low, shock chlorination makes sense if the water is exchanged
- If the chlorine level is too high, wait before swimming, alternatively reduce the chlorine level by adding fresh water
notice: In order to kill the existing algae, we specifically used algaecides. To prevent a new infestation, however, these agents are not necessary. With proper disinfection, the chlorine dissolved in the water is usually able to keep the algae under control and prevent green pool water.