Green Water In The Backyard Swimming Pool — Causes and Treatments

You clean your pool regularly, picking out all the leaves and debris with a net, but your pool water still turns green. You carefully go through all the steps of proper pool maintenance and believe you’re not missing anything. So why is the water green? There are actually three main causes of this problem including lack of chlorine, fallen pollens, and oxidized metals, each with its own specialized treatments. Don’t step into your swimming pool before you know what the problem is, and the water is treated. A green pool is a pool you should not be swimming in!

When there is a lack of chlorine, the first line of defence against bacteria is weakened. Algae will quickly grow and turn green. Algae is probably the most common reason behind discolouration, forming either a bluish green, yellowish green or dark green colour. When there’s an algae bloom in your pool water, mosquitos and other small insects will manifest and make it dangerous for you to swim in it. To remove the green algae, brush your pool and shock it to restore a balanced pH level, then eliminate all traces of algae with algaecide.

Another source of green swimming pool waters may be the pollens carried into your pool water by the wind. Even if you try to pick them up with sand filters, they will be small enough to seep through the holes. A small amount of pollen won’t make a significant colour difference, but as they build up, they will settle on your pool liner and make the water appear green. Although the swimming pool water looks unappealing, the pollen in your water can be quite harmless. Both the pool surfaces and your body won’t be damaged. But to restore the blue, pristine colour to your pool water, adding a flocculant can easily rid the fallen pollens.

Metals that have oxidized may also turn your pool water into a light green colour. They usually enter your pool through source water or from cheap algaecides. Sometimes if the pool water is too acidic, the metal parts of your pool, especially copper, will wear down and add metals into the water. When you shock your pool, the metal elements inside your pool water will be oxidized, thus turning green. Eventually your pool surface will be stained. If you have light coloured hair, your hair may even turn green. To remove the metals, add a sequestrate to group metal particles together, making them easier for pool filters to catch.

Having green water in your swimming pool is both unattractive and sometimes harmful to you and your pool. If you need more advice on how to treat your pool water and turn it back to its original condition, feel free to book an appointment with Seaway Pools & Hot Tubs. We have expert staff that know how to keep your pool looking and feeling great for you and your family. Please don’t hesitate to contact us at 905-294-8030, or on our toll free number 1-888-494-8030, or by email at

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