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  Richard A. Falk January 10, 2011 at 2:26pm

  One should also look at the About the Biofilms - Enzymes to the Rescue blog.  As I stated there, biofilms become a problem "once established" so the key is to prevent them from getting established in the first place.  If one cannot do that, then there are alternatives for prevention including these mineral-based products, sphagnum moss products, enzyme products, and some alternate media types such as recycled crushed glass.  The claim by some of the manufacturers of these products (such as Dryden-Aqua) is that channeling in sand filters is common with some saying that around 1/3rd of pools experience this problem due to biofilms.  I don't know if that is true, but if it is then it's more of a problem in commercial/public pools since properly maintained residential pools don't see this.  Out of the thousands of sand filters in (mostly) properly maintained pools at The Pool Forum and Trouble Free Pool, there is only one report of a sand filter with channeling (and it was very clumped) and was a pool that had a period of poor maintenance with no problems since.  The overnight chlorine demand test (with the filter running) is one of the easiest ways to detect such problems (other than inspection).  The manufacturer claims are also that the Combined Chlorine (CC) is higher under these situations.

   

  As shown in this link that sorts the Pinellas County, FL 1992 (1994) pool study data by FC, out of 486 pools, there were 49 or about 10% that had ZERO Free Chlorine (FC) and many others with very low FC/CYA ratios.  Around half of these pools were deemed bacteriologically unsafe based on study criteria.  More recently, the this 2008 CDC report summarizing over 100,000 inspections also had over 10% of pools with disinfectant violations including no disinfectant.  So assuming that there is some rotation of which pools get to near zero chlorine, it would not surprise me if up to 1/3rd of commercial/public pools had long enough periods with no disinfectant to allow biofilms to form, especially in sand filters where there are typically plenty of nutrients in high bather load pools between backwashings.

   

  There is also the experience of residential spa owners which due to the high bather load from small water volumes are closer to commercial/public pools and spas than to residential low bather-load pools.  There is no question that the wet testing with such spas along with manufacturing remnants in new spas requires special cleaning, such as by using Spa System Flush, but after that if the spas are properly maintained, biofilms and associated chlorine demand are not an issue.  In residential spas, if one uses Dichlor-only for sanitation, then the buildup of CYA does slow down oxidation and sanitation to the point where the water can turn dull or cloudy, but if one uses Dichlor initially and then switches to bleach (or to lithium hypochlorite), then one is usually able to go twice as long before changing the water and even then the water isn't dull or cloudy.  The chlorine demand when the spa is not in use does increase from around 25% per day towards a maximum of 50% per day, but a water change restores the chlorine demand back down again indicating that the demand is from something in the water (probably slow-to-oxidize organics) and not from biofilms which are not removed by a water change.

   

  I'm not saying that biofilms aren't real, but that the idea that you have to use a special product to prevent them is not true based on real pools.  However, for commercial/public pools with sand filters, there might be special techniques that need to be used to ensure that circulation through the sand is even since having disinfectant in the water doesn't help if there are dead spots where such disinfectant can get used up locally.  You can certainly use a biofilm prevention product if you want to, but should not feel that you have to unless disinfectant levels cannot be properly maintained or circulation (including through the filter) cannot be made relatively even.

   

  The one thing that high bather load pools and spas can and should use is supplemental oxidation because giving the entire burden to chlorine alone simply increases the amount of disinfection by-products that are produced.  Using ozone, enzymes, non-chlorine shock, or even UV (to some extent) can help significantly if systems are sized properly.
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  Al Neumann January 10, 2011 at 8:03am

  Don,

  AquaFinesse is a new product for me, and is definitely going to be on my watch list to learn more about it. I personally think that Biofilm Research is going to play a key role in solving many of the issues we face today in water and air quallity...at least for commercial pools. I agree with Richard in saying their are many products out there that claim effectiveness for Biofilms, but disagree with him that maintaining proper chlorine levels will have much of an effect on them. Many claim that they are a major source of chlorne demand, and I have a tendency to agree with them more so than not.

  Here's a link that explains the realities and difficulties of biofilm in pools and spas, which is quite good, as it is in laymans terms, so is easily understood. This article was written by David Knighton, and he manufactures a system for using shagnum moss. Although moss is on my radar, I'm not advocating it here. I offer it only because I think that the Biofilm article is quite accurate, and mimics the research by the Center for Biofilm Engineering at Montana State University. http://www.aquaticsintl.com/2009/jun/0906_techtalk.html
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  Richard A. Falk January 9, 2011 at 6:40pm

  As you can read from a couple of company responses in this thread, AquaFinesse is not an enzyme, but a combination of natural salts that they claim significantly reduces existing biofilms and inhibits biofilm formation.  By itself, it is not a sanitizer nor an oxidizer.  Since chlorine alone will prevent biofilms so long as proper chlorine levels are maintained, the product should be seen more like insurance in case one does not maintain proper sanitizer levels.

   

  There are many biofilm-reducing products on the market that claim to reduce chemical demand, including chlorine demand, but unless you've got channeling in your sand filter with lots of biofilm there or have insufficient FC/CYA ratios or let the chlorine get to zero for too long, these products won't reduce chlorine demand.  In outdoor residential pools (low bather load) the largest chlorine demand is from the UV in sunlight while in most commercial public pools (high bather load) the largest chlorine demand is from bather waste (ammonia and urea from sweat and urine, plus skin, etc.).  Unless one has a high overnight chlorine drop, then one doesn't have significant biofilms or at least they aren't affecting chlorine demand.

   

  Even products like enzymes that actually oxidize bather waste are mostly helpful in high bather load situations and not so much with residential pools unless such pools are poorly maintained with too low a chlorine or too high a cyanuric acid level (i.e. too low an FC/CYA ratio).