Why Is My Pool Green?

There is nothing better than dipping into a refreshing pool in the blazing midst of summer to cool off - apart from when your pool water has turned a horrendous shade of green. 

Trust us, you’re definitely not the only ones who’ve woken up one day and had your eyes alerted to the shocking green state of your swimming pool.

What happened? Is it safe? You may have a whole list of questions and rest assured, we have all the answers.

This article will explain why your pool water has turned green, what you can do to fix it and how to prevent this from happening again. 

Why is my pool green?

There are a handful of reasons as to why your pool water could have turned green, all of which can be fixed yourself or by calling a professional to do it for you.

why is my pool green

Reason 1 - Algae (Lack of Chlorine)

One of the most common reasons why pool water turns green is because there is a lack of chlorine or other cleaning chemicals in the water which has led to algae forming.

If chlorine is not added once algae begin to form, then the entire pool will turn green within a day, which is why many people will wake up with the shock of having a green swimming pool.

This is why people will uncover their swimming pools when the warmer weather returns and find their swimming pools bright green - because no one is adding chlorine or other chemicals to the water as no one is swimming in there during the winter. 

Reason 2 - Metals

Another reason as to why your pool water could have turned green is metals within the water.

Metals can enter the water through cheap algaecides, source water, or through metal components of the pool such as metal heaters. 

When you shock (add chlorine) to a pool that has metals in the water, the metals will oxidize and turn the water green.

You’ll want to get this problem sorted as soon as possible otherwise it could permanently stain the exterior finish of the pool.

This is often why people with natural blonde or dyed blonde hair experience their hair turning green sometimes as there are excessive metals in the water that have oxidized with chlorine. 

Reason 3 - Pollen

Pollen from nearby plants and trees could be turning your pool water green and as it’s too fine to be filtered out, it’ll continue to build up and therefore your pool water will remain green. 

Is it safe to swim in a green pool?

If your green pool water is due to algae, then we wouldn’t recommend swimming in there as this could also be a breeding ground for insects and mosquitos.

Generally, it’s not recommended for anyone to swim in pools without chlorine in the water. 

You may be questioning this, as many people do swim in lakes and ponds where there is a large ecosystem filled with bacteria and toxins, however, the aquatic animals will feed on these things, and therefore the water is safe to swim in.

It’s considered less safe to swim in a pool that’s turned green the darker it becomes. 

However, if you’re sure that the pool water has turned green due to pollen, then unless you’re severely allergic it’ll be fine to swim in the pool.

How to fix a green pool?

How to fix a green pool caused by algae

If you’ve concluded the problem is down to algae, then your next port of call is to shock the pool water with chlorine as this will kill the algae.

why is my pool green

You’ll also want to use some algaecide with the shock to break down the slime layer that protects the algae from the chlorine shock chemical. 

As well as adding algaecide and shocking your pool water to kill algae, you’ll want to brush the entire surface of your pool to break away the stubborn algae build-up so it is killed more easily.

You must make sure to keep pumping and filtering the pool to regain the balance 24/7 until the water becomes clear again. You may also want to vacuum the pool a few times to ensure there are no algae left. 

How to fix a green pool caused by pollen

Pollen is too fine to be filtered out of the pool and no equipment will permanently clear up the pollen in a pool.

Adding flocculant will cause fine particles to clump together in the pool which you’ll then be able to vacuum from the pool. However, pollen pool water is not harmful to humans unless you have allergies. 

How to fix a green pool caused by metals

You’ll need to as a sequestrant to the pool to help the metals clump together so then they can be filtered out of the pool.

Once the pool water is blue again, chemically clean the filter to ensure no metals are remaining and cannot go back into the pool. 

You’ll want to try and pinpoint how metals are getting into the pool to prevent it from happening again.

If it’s from source water you’ll want to continue using sequestrants every week to prevent the pool from turning green again.

However, if it’s due to metal components like a heater, you’ll want to bypass the heater and raise the alkalinity levels in the pool. 

Get a professional in

If you’ve tried and tested all the methods to fixing your green pool and nothing has worked, then it’ll be time to bring in a professional to take a look to see if there is a deeper issue.

If your pool water has turned a very dark green that looks almost black, we would skip trying to sort it out yourself and call in the pros. 

Regular chemical balancing and regular testing of the pH levels will ensure your pool water remains blue and clean.

If you don’t want to deal with the upkeep of having a great-looking pool, then we’d recommend hiring a professional pool person to come by every other week to test the water and make sure it’s right.