Mustard algae looks and behaves differently from most other algae found in swimming pools.  Virtually all pools in the Mid-South region are now exposed to mustard algae, which can appear even in pools that have had proper pool chemical care. 


What does it look like?

Mustard algae has a yellowish-brown "mustard" color.  Unlike other algae forms, mustard algae generally does not stick to the surface.  It is often difficult to identify as it closely resembles a fine-powered dirt sediment on the pool's floor.  

Mustard algae is easily brushed or vacuumed up, but it generally reappears within 24 hours.  Its very fine size allows it to pass through most sand filters and resettle onto the pool's floor.


Can I eliminate it?

Mustard algae is one of the most difficult of all algae forms to kill and remove from a swimming pool. Most traditional algaecides are not effective on killing and eliminating Mustard algae. There are many treatments available, but most have undesirable side-effects.  The most reliable procedure is as follows:

1.  Vacuum pool with the filter valve on "waste" position.  This will flush some of the settled mustard directly to the sewer.

2.  Adjust your pH to 7.2.

3.  Add 6 oz of Pool Baron's Yellow Clear per 15,000 gallons of water.  Apply directly into skimmer.

4.  Add 3 lbs. of Poolife Turbo Shock per 10,000 gallons of water.

5.  Add 2 oz. of Pool Baron's Ultra Clarifier per 10,000 gallons of water (pre-dissolve in a bucket of water and pour into pool).

6.  If there is any cloudiness to the water prior to the above treatment, also add 1# of Pool Baron's White Lightnin' per 10,000 gallons of water.


Have I been successful? 

Achieving 100% elimination of the Mustard algae is the goal.  If any of the Mustard algae remains "alive" after the treatment, it can quickly grow back into a healthy Mustard algae colony.   Should any signs of mustard algae be visible after 48 hours, repeat the procedure above AGAIN or apply an application of Pool Baron's Copper Rescue.


What if I have a Diatomaceous or Cartridge Filter?

Diatomaceous Earth (D.E.) and Cartridge filters must be thoroughly cleaned BEFORE the above treatment is undertaken.


Future Prevention

Using SeaKlear Algae Prevention Remover helps prevent and kill future mustard algae.  If the pool’s balance is properly maintained, there is little risk of the copper in this product causing a stain.  On dark-bottom pools, there should be no concern about using this product.  The best long-term prevention can be attained by adding and maintaining a 50 ppm level of Endure Water Conditioner to the water.

Related Articles:

My Pool Won’t Clear

Green & Cloudy Water


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