How To Remove Mustard Algae From A Pool

What was once an urban legend is now a real problem! More and more clients are telling us that they have noticed an odd sand-like substance in their pool. What is this pesky, yellow-looking stuff on the pool floor? Well you might actually have an outbreak of mustard algae, also known as yellow algae. In this blog, we’ll explain what it is and how to remove mustard algae from a pool.

What Is Mustard Algae?

Commonly thought to be a fairly rare algae although more frequently found in warmer climates, mustard algae is actually another form of green algae but is, as the name suggests, yellow-brown in colour. In it’s early stages, it is often mistaken for sand or dirt or a stain on the pool sides or floor and unlike green algae though, mustard algae is not slimy.

Mustard algae is, however, chlorine resistant, airborne, meaning it can survive outside of the pool and very stubborn. Not only can it stain your swimming pool, it can also live on all your pool equipment, pool toys, floats and togs! To get rid of it once and for all, you’ll need to treat everything that’s been in the pool water.

What Causes It?

Algae is like a plant and as such depends on elements such as light, water, carbon dioxide and nutrients to thrive. Poor water circulation, the incorrect use of chemicals and poor water chemistry can all contribute to the growth of algae in your pool.

The environment around the pool can also play a part in the development of algae. This can include things like hot weather, wind, rain, pets, plants and fertilisers.

While we can’t control many of these environmental factors, we can help to minimise the risk of algae developing in our swimming pools by ensuring good water balance and with the appropriate use of chemicals.

How To Remove Mustard Algae

  1. First things first: remove all the accessories from the pool and disinfect them with a chlorine based cleaner (not bleach).
  2. Machine wash your bathers and dry them in a dryer on a hot setting to ensure no spores are still clinging on!
  3. Check your pool chemistry. You need well-balanced water before you start adding any additional chemicals to ensure active chlorine production is optimised.
  4. Put all your pool equipment e.g. hoses, poles and any other accessories that may be infected, in the shallowest part of your pool so that when you ‘shock’ the pool is it disinfected.
  5. Apply a killing dosage rate of Bioguard MSA Extreme algaecide according to the label instructions.
  6. Brush the sides and floor of the pool with a good algae brush and vacuum the pool ‘to waste’ to bypass the cartridge and filters. You may want to ensure your pool is topped up with fresh water before you do this.
  7. Re-test the pool water to ensure the chemistry is still aligned and adjust as necessary.
  8. Shock your pool: applying a pool shock treatment will help ensure that any remaining algae spores are effectively killed off.
  9. Re-brush and re-balance your pool over the next few days. To restore sparkle, add Bioguard Polysheen Plus and/or Super Clear Clarifying Tabs as per the instructions.
  10. Clean and backwash the pool filter to ensure no mustard algae spores are hiding there.

And there you have it! You will need to re-test your pool again over the coming days and possibly repeat some of the steps above if it doesn’t completely clear up.

The best prevention is to maintain a healthy water balance to ensure your pool remains well-sanitised.