How to Clear an Algae Outbreak in a Swimming Pool | HASA (2024)

• March 4, 2020

The last thing any pool owner wants is to have an outbreak of algae during the summer. Well maintained pools should be free from algae, however there are some things that can turn a maintained pool into a green menace right at the height of swim season. Here are just some of the causes of algae outbreaks and how to clear algae this Summer.

Summer Storms
Rainstorms are notorious for bringing nitrogen into the atmosphere which can naturally make its way into the pool and convert into nitrates a food source for algae. Also when nitrogen in the air comes in contact with raindrops then it is converted to nitric acid which will be carried into the pool. Flooding can cause mud and debris that carries algae into the pool. Also, if the power is knocked out and the pump cannot work to circulate water then things can get bad fast, especially in the hot days of summer.

Pool Parties
Summer is the time for backyard pool parties and along with the increase and length of duration of people in the pool comes higher chlorine demand. Chlorine can be completely consumed within hours during a hot afternoon. This can lead to fast algae growth when the pool is packed with swimmers who bring dirt, bacteria, sunscreen and other organics into the water. Also, if guest bring their own life jackets, inflatables or even their swimsuits which have previously been in a lake or river, then algae can be carried directly to the pool. If the pool is not super-chlorinated, cleaned and thoroughly brushed soon after the pool party then algae can appear rapidly.

Fertilizer
Most fertilizers contain nitrogen and phosphorous two main nutrients for plant growth and algae is a plant. Spring and even summer can be the time that we are planting and renewing the backyard. The fertilizers used for lawns and flower gardens can make their way into the pool through over-watering or even via the wind. Once the hot weather hits and chlorine demand increases then algae have plenty of nutrients to get a strong foothold.

Lack of filtration and Circulation
Water that is moving is healthy water, water that is still will increase the potential of algae. It is imperative that during the hot summer months the pool receives efficient filter turnover time and good circulation throughout the pool. During the summer the pool should filter a minimum of 6-8 hours per day. Return jets should be positioned to prevent dead spots and to ensure the greatest amount of flow and movement throughout the pool. Many pool owners become concerned due to energy, however during the summer months any insufficient filtration can lead to additional cost from increased chemicals and treatments of algaecide. Filtration and circulation is vital during and after heavy swimmer loads.

What to do when the pool has become a swamp
Chlorine is still one of the most effective killers of algae so doing a super-chlorination of 10-20 ppm of chlorine can go a long way towards wiping out the algae. Liquid chlorine is an ideal shock for algae because it is fast acting and does not add cyanuric acid (CYA) or calcium to the water. Bromine has been shown to be an even faster killer than chlorine so choosing a two-part bromine algae system where you add the algae product and follow with a chlorine or a chlorine free oxidizer to produce active bromine. There are also ammonia salt products that can be used along with liquid chlorine as a shock. These systems can kill and remove algae within 24 hours. Immediately after adding algae kill products it is important to follow with a eco-friendly chitosan natural based clarifier to help floc and remove dead algae to the filter. The clarifier should be dosed at 3-4 times the normal maintenance and can continue to be used throughout the clean-up process. The pool filter should be run 24 hours until all algae has cleared. Once the algae are cleared the filter should be thoroughly cleaned. It is recommended to do a test for phosphates as dying algae can exude nutrients back into the pool water. A phosphate treatment may be beneficial at this stage. Also, a good preventative algaecide may be addedto prevent additional outbreaks through the end of the season.

Wrap it up with a good enzyme
You may have seen commercials lately showing oil companies harvesting algae. And what are they harvesting it for? Oil. Algae exudes a hydro carbon and can leave plenty of oily residue behind in pool water and in the filter media. Using a good broad-spectrum enzyme after a heavy algae growth can help clean the water and surfaces. Also, the enzyme will help break down any additional non-living organic material which could cause chemicals to degrade faster. So, the quick breakdown for a green pool in summer is:

1. Shock with liquid sodium hypochlorite or use a sodium bromide algae product along with the liquid
2. Follow immediately with a 3-4 times dose of chitosan- based clarifier
3. Run filter 24 hours and chlorine ensure good circulation and filtration ongoing
4. Thoroughly clean filter
5. Test and treat for phosphates if necessary
6. Add a good preventative algaecide
7. Use a broad-spectrum concentrated enzyme to clean up oil and non-living organic debris
8. Brush, brush, brush. One of the best ways to prevent algae is by regular maintenance brushing of the pool. There is no chemical that can replace the need for consistent brushing of the pool surface.

Now, the pool is clean again and ready for your customers to finish out the summer season with good quality water.

You can view HASAPOOL products to clear algae and keep a clean pool by clicking here.