Removing Biofilms From Swimming Pools

by Pool Builders on 03-14-2009 in Articles

Now that we know what biofilms are (learn about biofilms in our companion article), let's talk about HOW to remove them and prevent their return. Please remember that these methods and products do not KILL the biofilm and no statement is made to that effect.

Biofilms can be removed mechanically, chemically or "naturally." Mechanical removal uses hand or automatic vacuums, wall brushes, scrub brushes, filter cleaners, etcetera, physically remove the biofilm from visible places.

Visible places would be the filter cartridge itself, filter tank, vinyl liner, water line, ladder treads, skimmer baskets, etc. You can physically handle the object that needs to be cleaned. This is one of the reasons why we as Pool Professionals are so adamant about brushing the pool's surfaces on a regular, weekly basis. Brushing breaks up and lifts the biofilm off from its cozy environs enabling the chlorine or other sanitizer a better opportunity to kill it and the filter to remove it. Be careful however to regularly clean & chemically clean the filter to remove the accumulations of "filtered" biofilms from the filter media - whether it be sand, DE or cartridge.

Keep in mind that biofilms are a direct contributor to chlorine demand, causing the pool to use significantly more chlorine, bromine or biguanides than if none were present. Remove the biofilm, remove an important component to chlorine demand.

In hard to reach places like pool plumbing lines & inside heaters, biofilms need to be removed Chemically. This is where so much biofilm (and about 99% of the bacteria) accumulates and thrives. Biofilm is left alone. It has all that it needs - a surface, moisture, and nutrients floating by. Keep in mind that biofilm doesn't need sunlight - it's not an algae so sunlight is not one of biofilm's needs. Biofilm does need "warm" water - 90 F or better for optimal growth, but as long as it's not cold, the biofilm will survive and grow just fine thank you.

Tried & true products such as natural enzymes (Natural Chemistry® Pool Perfect, Pool First Aid, etc.) "eat up" much of the nutrients and other waste that contribute to biofilm growth thereby stunting it. But as biofilms become more resistant and more proliferate, a new arsenal of products must be considered & used. Newer products such as AquaFinesse(TM) Pool Pucks are added to the pool skimmer and quite rapidly remove the biofilm from the hidden surfaces. AquaFinesse(TM) products have been successfully used in the European market and in industrial applications for several years. As with the physical removal products, loosened & removed biofilm particles must be filtered out of the water and then removed from the system entirely. After initial application, you will notice that the filter becomes rapidly clogged as the filter traps all of that used biofilm. Cartridge and diatomaceous earth filters must be chemically cleaned to restore the filter to a proper working condition. If biofilm removal has never been done before, it may be necessary or even advantageous to replace the filter media - especially in older swimming pools. These products are completely compatible with all pool care chemical systems (chlorine, bromine, biguanides, ionizers. salt).

An even newer, "gentler" natural way to remove biofilm is using sphagnum moss. In testing by Montana State Univ. Center for Biofilm Engineering, sphagnum moss was found to be an excellent preventive and remover of biofilm. It was noticed in many ponds and lakes the world over that where sphagnum moss lived and thrived, water quality of those lakes and ponds was "potable" or drinkable without the need for filtering or chemical sanitizing. New patented products such as the patented PoolNaturally(TM) and SpaNaturally(TM) use eco-friendly, eco-processed sphagnum moss in disposable, consumer friendly pouches to remove biofilms and prevent biofilms. Studies are further showing that pool water treated with sphagnum moss stays better balanced (natural buffers are present in the moss) and is "gentler" for swimmers. PoolNaturally(TM) sphagnum moss pouches are replaced on a monthly basis for optimal effect. Sphagnum moss products work with all chlorine, bromine, salt systems, and ionizers but are NOT compatible with biguanide products such as BioGuard® Soft Swim® or Arch Chemicals® Baquacil®.

The bottom line for the pool owner and customer is a longer life of the pool and pool equipment (filter, heater, rails, ladders, etc.) due to the removal of biofilms as well as biofilm scaling. Chemical consumption should and will show a marked decrease as chlorine, bromine & other sanitizers can concentrate on the 1% of "planktonic" (free floating) bacteria present in the water. Easier water balance, less shocking, etc. Remember to continue a regular water testing and chemical maintenance routine - adjusting pH, total alkalinity, calcium hardness as necessary. Normal shocking oxidizes bather and environmental waste (bird droppings, human sweat).

It is true that only time will prove the efficacy & efficiency of these new treatments, but the studies so far look extremely promising.

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