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2nd July 2020

Foaming in swimming pools and spas can be caused by detergents, soaps or shampoos in the water.  This could have happened after cleaning the swimming pool surrounds or if a bather enters the pool or spa without rinsing off shampoo or other skin products.

Probable causes

  • Detergent, soap or shampoo
  • Excess algeacide
  • Excess water clarifier

Foaming can also occur in swimming pools if shower water from the changing area is allowed to drain into the pool. It should be noted that certain detergent-based products such as patio cleaners are incompatible with swimming pool water and they should be kept well away from the pool area.

Also, some pool or spa chemicals, such as algaecides and water clarifiers can cause foaming when added in excess.


Action to be taken:

To reduce concentration of algaecides and/or water clarifiers

  • The only practical way of reducing excess concentrations of these water treatment chemicals is to dilute with fresh water.
  • Due to structural considerations relating to swimming pool design etc, great care should be exercised when draining large quantities of water from a swimming pool and the advice of your approved swimming pool dealer should be sought regarding the maximum quantity of water that it is safe to replace in one operation.


To chlorinate (oxidise) out detergents

  • It is possible to ‘react out’ detergent based products such as cleaning materials, soap and shampoos by applying a shock dose of unstabilised chlorine such as Fi-Clor Superfast Granules. Before adding this product, ensure the pH is within the range 7.2 – 7.6. If it is not, the following corrections should be made.
  • To lower the pH, dose pH & Alkalinity Reducer. With the circulation running, distribute evenly around the pool or spa, avoiding the skimmers.
  • To raise the pH, dose pH Increaser. With the circulation running, distribute evenly around the pool, avoiding the skimmers.
  • Having adjusted the pH, shock treat the pool using Fi-Clor Superfast Granules. Dose rate guide can be found on the back of product container. Broadcast the product evenly over a wide area in the deepest part of the pool or spa and keep the circulation running.



WARNING: Do not mix Fi-Clor Superfast products with any other types of chlorinating compounds (even other products in the Fi-Clor range) either in the dry state, or in the skimmer. Fire or explosion may result. If using with other products, dose them separately into different areas of the pool.

  • Run the circulation for 24 hours and re-test the free chlorine. Bathers should not use the pool or spa under any circumstances if the free chlorine reading is above 10mg/l (ppm), irrespective of sanitiser type. If a swimming pool is unstabilised and chlorine sanitisers such as calcium hypochlorite or sodium hypochlorite are being used, bathing should not re-commence until the free chlorine level has fallen to 3.0mg/l (ppm) or below. For a fully stabilised pool, bathing may be possible if the chlorine is only a few parts per million above the recommended 4.0mg/l (ppm) maximum. However, caution should be exercised and bathing stopped if any eye or skin discomfort is experienced.


To use a No Foam product (Spas only)


  • If you have a hot tub or spa you can use a no foam product. This will prevent foaming which is a common issue in spas.

Apply this product directly to your spa water whilst the spa pump(s) are turn on, to aid distribution.