It can be disheartening having to cancel yet another pool party because your pool water is green. That green colour you see is caused by algae in your swimming pool. Algae is a plant like organism that can appear as green/blue, a yellow/mustard colour, or black. Let’s take a closer look at what kind of algae may be plaguing your pool.

  • Green or Blue Pool Algae is the most common swimming pool algae, as it is attracted to unclean areas. It can stick to your liner or free float in the water. This is why it is important to regularly run your filtering system. Luckily it is the easiest algae to remedy: just sanitize and continue regular maintenance around your pool.
  • Yellow Pool Algae or Mustard Algae is the type of algae that grows on the walls of the swimming pool in spots that don’t get a lot of sun. Often it is assumed that it is sand or pollen because of its colour. This is harder to get rid of as it requires you to super shock your pool.
  • Black Algae is by far the stinginess of the three, but thankfully it is relatively uncommon. This type of algae comes with a mind of its own, and strong roots. These roots will grow deep into the plaster of pool walls, and will appear even if you are taking care of your pool normally. In order to rid your pool of black algae, find a strong pool brush and scrub, plus super shock your pool until the infestation is gone.

Now that you understand what the types of algae are, it is important to understand why your swimming pool water is green. Basically all this means is that there is algae present, and you may need to shock your pool, as well as start a regular chemical schedule. By running your pool’s pump regularly any remaining bits of algae will find it hard to grow when the water is moving. Algae may also look for a dark place away from circulation, so always give a thorough check around problem areas like under your ladder, your pool steps, any corners or crevices, and so forth.

Let’s take a look on how to rid your pool of algae, so you can fight the heat and get back to your clean, comfortable swimming pool.

1. Shocking Your Pool

This is the least expensive option of the three. Shocking your pool means super chlorinating it. To shock your pool you require a stirring stick, a bucket, and pool shock. If you have a vinyl liner, dissolve shock in bucket prior to adding to the swimming pool. When you shock your pool to fight against algae, it is important to note that there are three different stages of algae in which different amounts of pool shock are needed: light green, dark green, and black green. The shades of green indicate the amount of algae in the pool water.

  • If your pool water is light green in colour, you will need to double shock your pool. If your pool is 10,000 gallons of water or less, you will need to add 2 single pound bags of shock. If your pool is 20,000 gallons or less add 4 single pound bags, 30,000 gallons or less, add 6 single one-pound bags to your swimming pool.
  • If your pool water is dark green in colour, this requires triple shocking your pool. Therefore the required amount is 3 one-pound bags of shock/10,000 gallons, as opposed to only two for light green water.
  • If your pool water is black green in colour, this requires a quadruple shock. This means that you will add another one-pound bag of shock/10,000 gallons of water, meaning that for every 10,000 gallons of water you will require 4 pounds of shock.
Floccing Your Swimming Pool

Floc, aka Flocculant, is a chemical that works by moving all small particles to the bottom of the pool to help you when vacuuming your pool. It is a fast acting way of ridding algae, provided you have done this correctly. This is a relatively inexpensive option, but requires some elbow grease. Here is how to floc your swimming pool:

  • Shut of your pump and ensure that water is no longer flowing from your filter by putting it into a recirculate or recycling mode.
  • Add recommended amount of Floc to your pool.
  • Let the water circulate for about 2 hours to get the chemicals mixed in, then shut it off.
  • After letting it sit overnight, the chemicals will have all sunk to the floor of the pool. Set your filter onto waste mode and start vacuuming.
  • Add garden hose to the pool, turning it on while you vacuum the pool. Since you set your filter to waste mode, you will lose pool water.
  • Continue vacuuming out the bottom of your pool, slowly. As the remaining debris will be thick and dirty. If you are having trouble seeing what you’re doing, shut off your pump and let it resettle. Then proceed to continue vacuuming.
  • Now that you have finished vacuuming your pool, double shock to make sure all remaining algae and debris is destroyed.
Use Swimming Pool Algaecide

If your swimming pool is prone to algae, using an algaecide as a preventative measure may be another suitable option for continued maintenance. However, there are algaecides that contain algae killers (like copper or silver), and if applied in large doses and mixed with shock, it may be enough to do the trick. Note that because these types of algaecides contain metals, it may cause staining. Another type is called poly quats, which is to be used in small doses, but cause excess foaming in the water. Thus, it is important to carefully read the information on the bottle to select the one that’s right for you.

All in all, when it comes to selecting the best method for ridding your pool of algae it is really up to your own discretion and preference. Pool professionals stand divided on what is the best recommended course of treatment. That is why it is important to educate yourself, know your options, and treat the algae as soon as it infests your swimming pool. The first method is the most common, least expensive option that generally does the trick. Although it may require a couple of tries. The third method is the best method for preventative measures if your pool is prone to algae. The second method requires the most work, but it can also be quick and quite effective.