Pool Is Green Yet Clear - Why?

Pool Looks Green But Water Is Clear - Why?

If you have noticed that your pool water is clear but has a green tint, it can be confusing. Because dirty pools with algae and other similar issues tend to be cloudy, it can sometimes be difficult to pinpoint the cause of your green and clear pool.

In this article we will discuss a couple of reasons that your pool looks green but the water is clear, and steps that you can take to get rid of this green hue.

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Reasons Your Pool Looks Green But Water Is Clear

Algae Infestation

Although many types of algae cause the water to become cloudy, this is not always the case. It is possible for your pool water to be clear but have a green tint due to an algae infestation, and these types of algae problems are usually not very severe.

Algae growths can be caused by imbalances in pH, total alkalinity, and cyanuric acid, all of which may lower the effectiveness of your chlorine.

Active algae also tends to make your chlorine levels drop faster than normal. If you suspect that you have algae, it is a good idea to test various chemical levels of your pool.

You may also be able to notice algae building up on the surfaces of your pool upon closer inspection.

This buildup can sometimes make the water appear green even though the algae is actually stuck to the pool surface. If this buildup has a slimy or moss-like texture, it is made of algae.

It can sometimes be tricky to determine if you have algae in your pool, especially if it does not build up on surfaces. In general, if the chemistry of your pool is reading at normal levels and there is no increased demand for chlorine, it is unlikely that you have algae in your pool.

Oxidising Metals

If you do not have an algae infestation, the reason that your pool looks green but the water is clear can be due to oxidising metals in your water.

Many different dissolved metals and minerals are present in pool water. These can be introduced to the pool through the water that you use to fill it, and can also be introduced through other chemicals.

Copper, for example, is a metal that is present in many formulations of algaecide. While this dissolved metal is completely harmless to swimmers and very effective at killing algae, once it begins to oxidise in your pool it can turn a shade of green.

Other minerals and metals that are present in your water may oxidise at the same time as copper, creating different variations in this green hue.

How To Get Rid Of Green In Pool

Cleaning Up Algae

If you have identified an algae problem in your pool, take steps to remedy it. To begin, it is advisable that you perform a shock treatment. You may use a chlorine-based or non-chlorine based shock treatment for this purpose.

If you have used an algaecide recently, it is important to avoid chlorine based shocks.

In this case, a non-chlorine based shock product is advised. While this shock treatment will not remove the algae particles from your pool, it will kill them off and prevent them from spreading.

Approximately a day after using the shock treatment, you may consider adding an algaecide to your pool. These should not be used as a first line of defence, but when they are used in small doses after a shock treatment, they significantly reduce the chances of any algae regrowth.

Over time, your filter should remove any dead algae from your water. If algae has accumulated on the surfaces of your pool, it may be necessary to scrub and vacuum these areas in order to prevent algae stains from developing.

Removing Dissolved Metals or Stains

When removing dissolved metals from your pool, you will first want to determine if these particles have attached to the surfaces of your pool. Metals that are oxidising in the water require a different type of treatment than those that have caused stains.

If you have metal stains forming in your pool, use a stain remover. When these products are used according to the instructions, they remove stains from the surfaces in your pool while working to prevent them in the future.

If you only have metals oxidising in your water rather than on your surfaces, use a metal removing solution. These products are sequestering agents, meaning that they work to keep dissolved metals incorporated into the solution of your water and prevent oxidation and stains.

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.