General water quality

Measure the pH and free chlorine, e.g. with a pool tester. The pH should always be between 6.5 – 7.2, this is also very important for skin compatibility. The optimum content of free chlorine is between 0.3 – 1.5 in private pools. Rule of thumb: always adjust the pH first, then chlorinate !!! The flocculation depends on the pH. Wash out the cartridge filter and back-flush the sand filter regularly. The circulation pump should run without interruption for at least 10 hours each day. Keep all parts of the swimming pool free from coarse dirt and pay attention to the water level so the skimmer and overflow channel function correctly. Add chemicals consciously and at short intervals. Regular checking and correction when necessary are the decisive factors for water quality and your well-being. "The more the merrier" is not always correct, always add chemicals exactly according to the label or your specialist dealer's instructions. Too much chemicals pollute the water and the environment, and can cause unexpected problems. The limit values must be adhered to.

Cloudy water

This is produced by turbid material in the water, which can be caused by organic residues (skin flakes, sun-screen cream etc.) but may also indicate micro-organism growth in the filter. In public swimming baths, problems in the pool hydraulics may also be the cause. Check the pH and if necessary reduce it to <7.0, this increases the effectiveness of the chlorine. Carry out pulse chlorination exclusively with Solid-Chlor®/Hypochlorit CA, check the pH again and adjust to <7.0. You should also put flocculating cartridges or POOL Floc Tab Duplex in the skimmer or use Liqui-Floc®. This increases the filter cleaning effort for cartridge filters. Check the sand filter, clean it with Oxidur powder and/or change the sand. Suck the cloudy materials away. In the public area the filter flushing should be checked and optimised if necessary.

Green or brown water

This is caused by metals and/or algae in the water. This problem occurs to a greater extent with spring water. Use Härtisator FE Plus to remove and avoid the green discolouration.

Green water and slippery green walls

A problem in the water treatment, it involves the growth of algae and micro-organisms. Observed particularly after hot muggy weather with thunderstorms. Can also be caused by excessive phosphate content in the water. Carry out pulse chlorination with Solid-Chlor®/Hypochlorit CA and use an algicide (non-foaming Algesan or low-foam Algipon). Back-flush the filter and let the pump run throughout the whole day. Mechanical cleaning of the pool walls and sucking away the algae is also advisable. For recurring problems and proven elevated phosphate content in the water, you should use Liqui-Floc® La or POOL Floc Tab Duplex regularly. If necessary ask your supplier to carry out a water analysis. 

Slippery brown/black walls

This involves stubborn brown and/or black algae. Use Solid-Chlor®/Hypochlorit CA for pulse chlorination and add silver solution as well. Here again it is important that you adhere to the pH.

Strong chlorine smell, reddened eyes

This is caused by chloramines and/or combined chlorine, i.e. free chlorine that has already reacted with organic substances. The pH may be either to high or too low. In the case of public baths the filter flushing may be insufficient. Adjust the pH to 6.5 – 7.2 and carry out a pulse chlorination with Solid-Chlor®/Hypochlorit CA. Check the filter for contamination and if necessary change the cartridges and/or sand.

Lime deposits

These deposits can form with very hard water. However, the problem can also be caused by an excessively high pH >7.4 or high water temperatures. Use Härtisator and adjust the pH permanently to <7.2. Clean the affected areas with K-Cleaner SF (do not use on stainless steel!) or with K-Cleaner SV for very heavily encrusted deposits.

Deposits of grease on pool edge

Caused by organic substances (skin flakes, sun-screen cream, environmental pollution etc.). Remove the dirt using an alkaline cleanser. Use Flamingo® Beckenrandreiniger to clean by hand or Ranisan Foam (to clean by high pressure cleaner with foam lance).

Corrosion of stainless steel parts

The chloride content in the water is too high and/or the pH is too low. The pH should always be between 6.5 – 7.2, increase the inflow of fresh (make-up) water and use exclusively sulphur-based pH reducing agents.

Black stains and/or green hair

The copper content of your water is too high. This can be caused by pipework corrosion of an algicide containing copper. Our Algesan and Algipon algicides do not contain copper. Carry out additional flocculation of your swimming pool with flocculating cartridges, POOL Floc Tab Duplex or Liqui-Floc®. Here again the pH must be adjusted to 6.5 - 7.2.

Water is cloudy/green or similar, but all values are correct

There is something wrong with the redox potential in your swimming pool water. If you do not have the means to measure this yourself, have it checked by a specialist dealer. An equilibrium state becomes established after some time in any oxidations process – as also occurs in water. This state can be measured electrically: the Redox voltage is measured as an electrical potential between the water and a reference electrode. The oxidizing substances in the water predominate when the Redox potential is positive. For treated swimming pool water the value should be between 700 mV and 900 mV. A high Redox potential means that the pure water contains almost no further reducing and/or bio-available substances. For example water can be considered to be sufficiently disinfected at a Redox potential of 740 mV and a chlorine content of 0.3 mg/l, but not at a Redox potential of 600 mV and a chlorine content of 0.6 mg/l. You increase the Redox potential by pH correction and chlorination using Solid-Chlor®/Hypochlorit CA.

How do I make measurements correctly?

1. The cover/lid of the Pool-tester is removed and the chambers/compartments rinsed with the water that is to be tested.
2. Put one Phenol Red tablet directly into the left-hand compartment, after tearing open the foil/film but without touching it with your fingers.
3. Put one DPD No. 1 tablet directly into the right-hand compartment, after tearing open the foil/film but without touching it with your fingers.
4. Fill the compartments ¼ full with water and crush or completely dissolve the tablets.
5. Now completely fill the compartments with water.
6. The cover/lid is pressed firmly onto the Pool-tester with the arrow symbols pointing towards the observer.
7. The tablets dissolve quickly. The water sample is mixed thoroughly by rotating the Pool-tester.
8. To read off the measured values, hold the Pool-tester up to the daylight. The associated measured value is read off at the point where there is complete or the best possible correspondence between the coloured solutions and the colour scales.
9. The value at the left-hand side is the measured pH.
10. The value at the right is the free chlorine content (mg/l).

• Touching the reagent tablets with the fingers causes errors in the measured values.
• The measurement results are read off immediately after fully dissolving the reagent tablets in the water sample.
• Free chlorine above 10 mg/l may bleach out the colour indicator.
• pH values below 6.8 always give a yellow colour.
• Water samples with low carbonate hardness (SBV 4.3<0.7 mmol/l) may give incorrect pH values, because there is insufficient buffering capacity in the water at a value of <0,7 mmol/l.

Pool tester does not display any measurement result

Probably the chlorine content in your water is too high ! When measuring with the DPD method, the measurement water in the measuring cell decolourises if there is too much chlorine in the water (normal: pink colouration). You think you have insufficient chlorine and you add even more. You can check this by adding one DPD tablet to your measuring cell. If the tablet briefly turns pink at the surface and then the solution remains clear on shaking, you have too much chlorine in the water. This method can work only if the pH is between 6.5 – 7.2. It is absolutely essential that you add fresh (make-up) water to your pool or that you neutralise the chlorine by adding Antichlor. You should also check the shelf-life expiry date of the test tablets.


The pH should be between 6.5 – 7.2. Stop the input of chlorine, chlorine must be no longer detectable (this takes about 5 - 7 days). Reduce the water level to below the skimmer and empty the external pipes. Put ice pressure buffers into the pool to compensate for the ice pressure. When the total chlorine content is <0.01 mg/l, distribute Wintersan uniformly into the pool and if necessary cover the pool over. Please note, Wintersan is not an anti-freeze.operating pressure.A high entry velocity into the filter is also disadvantageous.

Too much chlorine in the water

1. Fresh (make-up) water is suitable only if the excess is slight. Maximum 0.2 - 0.3 mg chlorine/l above the set-point value.
2. Reducing agents are considerably more effective, but over-dosing them causes problems when adjusting the required chlorine value .
3. Antichlor (Fixnatron), a dry, granular product, does not lose its activity even when stored for a prolonged time. Its good solubility in water guarantees that it acts quickly. The necessary amount is calculated from the difference between the actual and the desirable concentration. Example: chlorine content 3 mg/l, set-point value 0.6 mg/l. 2.4 mg/l needs to be destroyed with approx. 2.4 mg/l of Antichlor. Dissolve the Antichlor completely (no residue). Distribute the calculated amount uniformly over the water surface with a watering can. After mixing sufficiently, determine the chlorine content (add more if necessary).
4. Hydrogen peroxide can be used in the same way. However, the quantities depend on the actual content of active ingredient (as - H²O²). Example: chlorine content 3 mg/l, set-point value 0.6 mg/l. 2.4 mg/l needs to be destroyed with approx. 4 mg/l of hydrogen peroxide (approx. 30% H²O²). Distribute a portion of the calculated amount, equal to a maximum of half of the quantity, uniformly over the water surface;after mixing sufficiently (circulation), re-determine the chlorine content (then adjust the remaining quantities again if necessary).Caution ! Hydrogen peroxide can be stored for only a limited time in cool rooms at the as-supplied concentration.An overdose is detectable as combined chlorine.
5. Active charcoal in various forms can also be used for dechlorination.Addition takes place upstream of the filter, and it is removed during the next filter flushing. This procedure not only degrades chlorine but also adsorbs organic compounds; chloramines.

Powdered active charcoal should be used only if the filter does not have an excessively high operating pressure. A high entry velocity into the filter is also disadvantageous.Fluidising filtration is recognisable as filter bed unevenness; it may possibly allow the charcoal powder to pass through. Addition of powdered active charcoal and flocculating agent should take place in parallel.When combining the process described above, organism growth may occur if filtration and/or filter flushing is/are incorrect.