Clear green water after filling: iron, copper or algae?

Quick answer: Clear green water often means metals, not algae. First adjust the pH, use a metal-removal product and filter; only add shock chlorine based on measured values.

People often describe the water as clear but colored. That’s a different problem from cloudy green water full of algae. With well water and some tap water sources, disinfection can oxidize metals and the water turns green or brown.

• Iron, manganese or copper in the source water.
• Oxidation of metals after adding chlorine.
• Low alkalinity and fluctuating pH.
• Corrosion of metal parts or unsuitable copper-based products.

1. Check whether the water is clear or also cloudy.
2. Measure the pH and adjust it according to the chemical instructions.
3. Use a metal-removal or metal-stabilizing product.
4. Let the filtration run and clean the filter regularly.
5. If cloudiness forms, use a flocculant and vacuum the sediment.
6. Next time, when filling from a well, use a metal-removal product preventively.

• Don’t confuse clear discoloration with algae.
• Don’t repeatedly shock-chlorinate the water without measuring.
• Don’t use copper-based products if you’re already dealing with copper.

• For well water, get an analysis or at least watch the reaction after chlorinating.
• Clean the filtration and pipework before the season.
• Keep the pH stable so metals don’t precipitate as much.

Call an expert if the metals return after every top-up, stains appear on the liner, or you’re not sure which chemicals suit your equipment.

Can I identify metals with test strips?

Regular strips usually measure pH and disinfectant, not iron or copper precisely. A lab analysis or a specialized test will help.

Is clear green water safe for swimming?

Without measuring disinfectant and pH, this can’t be confirmed. Color alone isn’t enough to judge hygiene.