Green Water, Cloudy Water: Quick Diagnosis and Solutions
You arrive at your property on a summer Friday evening, ready for the weekend, and the pool greets you with green or milky water. This is one of the most common scenarios in the Gulf of Saint-Tropez during peak season. The good news is that most cases can be resolved within 24 to 48 hours with an accurate diagnosis and the right steps. Here’s the method used by the professionals at POOLRITUAL.
Green Water: Understanding What Happened
Water that turns green is almost always a sign of an algal bloom. These microorganisms thrive when the disinfectant (chlorine or equivalent) drops below the effective threshold, usually after a heat wave, a prolonged absence, a thunderstorm, or a pH imbalance.
The green color can be pale (suspended green algae), deep (algae attached to the walls), or tend toward black (mustard or black algae, which are more persistent). The intensity of the color directly determines the treatment protocol.
Cloudy or milky water: another sign
Cloudy, milky, or whitish water is not caused by algae but by a mineral imbalance or inadequate filtration. There are three main causes: an unbalanced pH or TAC that causes calcium carbonate to precipitate, a saturated or clogged filter, or a buildup of organic particles that the disinfectant has difficulty oxidizing.
In the Var region, the natural hardness of the water and the summer heat make this phenomenon common in July and August, especially after heavy use of the pool.
The Five-Minute Diagnosis
Before taking any action, a complete water test is essential. Key parameters: pH (target 7.0 to 7.4), free chlorine (1 to 2 mg/L), TAC (80 to 120 mg/L), TH (10 to 25 °F), stabilizer (cyanuric acid, 30 to 50 mg/L maximum). A test strip provides an initial reading, but a photometer offers much greater accuracy.
Also check the condition of the filter, the pressure on the pressure gauge, and the flow rate at the discharge points. If the pressure gauge reading rises above the reference value, this indicates that the filter is clogged.
Protocol for Green Water
Step 1: Adjust the pH to between 7.0 and 7.2 (a pH that is too high neutralizes the effectiveness of the shock treatment). Step 2: Perform a shock treatment with unstabilized chlorine at a high dose (generally 20 g/m³ for a moderate case, up to 30 g/m³ for a severe case). Step 3: Add a curative algaecide. Step 4: Run the filtration system continuously for 24 to 48 hours.
Step 5, essential: Clean or backwash the filter as soon as the water begins to clear. Dead algae accumulate there and could release their nutrients into the pond.
Protocol for Turbid Water
If the water is cloudy but not green, first check the pH and TAC. If the pH exceeds 7.8, lower it gradually; clarity will often return within a few hours. If the problem persists, a flocculant (in a bag or liquid form) will clump the fine particles together, making them filterable.
In any case, cleaning the filter is a mandatory step. A sand filter must be backwashed until the water runs clear; a cartridge filter must be disassembled and chemically cleaned.
When to Call a Professional
If, after 48 hours of proper treatment, the water quality does not improve, it means that an underlying factor has been overlooked in the analysis: an excessively high level of stabilizer blocking the chlorine, an excessively high phosphate level feeding the algae, a silent malfunction of the salt chlorinator, or a circulation problem. A pool professional equipped with a professional photometer and hands-on expertise will resolve the issue in a single visit.
POOLRITUAL provides emergency service throughout the Gulf of Saint-Tropez, offering a comprehensive diagnosis and documented repairs. For customers with maintenance contracts, these issues are anticipated and addressed before they even arise.
FAQ — Frequently Asked Questions
How long does it take for green water to become clear again?
With a properly conducted shock treatment and continuous filtration, slightly green water will clear up within 24 to 48 hours. Severe cases (black algae, bottom not visible) may take 3 to 5 days and require several treatment cycles.
Is it safe to swim in murky water?
No. Water where the bottom is not visible poses a real safety risk (it’s impossible to see a swimmer in distress) and indicates an imbalance that can affect the skin and eyes. Wait until the water becomes clear again.
Is shock chlorination harmful to the pool lining?
At normal doses and with the correct pH, no. However, repeated overdoses or a shock treatment applied when the pH is out of balance can discolor a liner or damage a seal. That’s why precise dosing is so important.
CONTACT POOLRITUAL
POOLRITUAL — High-end pool specialist in the Gulf of Saint-Tropez
79 Place de la Gare, 83240 Cavalaire-sur-Mer
poolritual.com
