"Mustard Algae" is probably the MOST misdiagnosed form of algae.  Mustard algae  is a chlorine-resistant form of green algae (yellow-green to brown in color)  typically found in sunbelt areas (Florida, California, Texas). It often resembles dirt or sand on the bottom or sides of a pool. Mustard algae can be very easy to transfer & cross-contaminate another pool (a neighbor or a public pool).

In our market area (Fairfield county CT), the number of TRUE Mustard Algae cases that we treat can be counted on ONE HAND in most seasons.  

Mustard Algae has these certain characteristics: It can be brushed away very easily, but returns quickly to almost the exact same location. Although it usually creates a large Chlorine demand (you have trouble maintaining a solid chlorine reading or residual (1.0 - 2.5 ppm), it has been known to survive in high levels of Chlorine (over 6.0 ppm).  It is not necessarily "slimy".  The pool water tends to be otherwise clear. Can be mistaken for copper or iron staining (if it brushes away, it's algae).

It is extremely important to remove mustard algae growth from equipment (including the back of underwater lights & ladders) and bathing suits to avoid cross or recontamination of other pools (mustard algae spores are physically transported to a neighbor's pool). Pool equipment can be left in the pool during product application or cleaned separately with a mild cleaning solution. Rinse thoroughly if equipment is used in a SoftSwim® pool. Bathing suits should be washed with detergent as directed on garment label.

Mustard algae will usually create a fairly large chlorine demand, although it can survive in high levels of chlorine.

In SoftSwim pools, mustard algae will deplete SoftSwim Clarifier.

Treatment:  

1. Have water properly analyzed. BALANCE THE POOL WATER. Proper pH, total alkalinity & calcium hardness are essential for the treatment to work.
2. Prior to and during treatment, the algae MUST be thoroughly brushed in order to "break open" the slime layer.  Failure to do this critical step will prevent the treatment from working. 
3. Pools treated with chlorine or bromine should aggressively shock with chlorine (Burn Out or Smart Shock) and use a good quality algicide such as Spot Kill, Back Up, Algae All 60 or Banish in extreme cases. 
4. Follow up either method with Optimizer Plus.

Prevention:

1. Maintain good, solid sanitizer levels all of the time.
2. Run the filter a minimum of 10 hours per day, everyday from opening to closing.
3. Vacuum the pool weekly.
4. Brush the pool walls & surfaces weekly (vacuuming doesn't count).
5. Shock the pool weekly.
6. Add algicide weekly.
7. Regularly clean solar blankets, ladders, pool toys, etc.
8. Use the pool.

Download FREE brochures to learn about pool care needs & problems.

Treating algae with Sodium Bromide.  Click here for all of our Algae treating products. 

Click here to purchase the chemicals mentioned in this article