Swimming Pool Expert Witness & International Watershape Consulting Engineer

Forms of Chlorine Sanitization

Large residential and commercial aquatic facilities need to perform a complete evaluation of the various form of chlorine sanitization available, before committing to a method.

Calcium Hypochlorite - Cal Hypo

It has the word "hype" in it's name for a reason.  While it provides the most inexpensive forms of chlorine, is carries with it a lot of hidden expenses.

Maintenance - the high levels of calcium in the compound cause clogging of the feeders, injectors and in severe cases even the plumbing.  The only way to remove these deposits is to physically chip them off or to saturate the deposits with muriatic acid.  DANGER: soaking these deposits in muriatic acid may cause an explosion and will form deadly mustard gas (chlorine gas).  Mustard gas will permanently burn and scar the lungs and sear the eyes.

Maintenance of the feeders is both dangerous and time consuming.  There is NO EASY way to keep the feeders clean.  The salesman is looking at his commission from reoccurring sales of calcium tablets... ad nauseam.

Water Balance - The high levels of calcium are also placed into solution within the pool water.  Very quickly the water become over saturated with calcium and the pool becomes difficult to balance.  The water gets a cloudy appearance.  Late in the day, the water appears murky and milk like.  The only way to reduce the calcium content is to DUMP precious water - that's right, drain the pool & dilute the water with fresh water.  

If the make up water (fill water) is ran through a water softener prior to entering the pool, then this ZERO calcium water will dilute calcium laden water, slowing the build-up - that will still occur (just slower).

Financial Interest - Most firms that specify calcium hypochlorite, sell the erosion feeders.  Most will also gladly contract for the supply (sell) of the cal-hypo briquets.  The equipment that they sell, states that the warranty is void, if another brand of briquets is used in their feeder.  This guarantees the specifier will have a client for life - or until the client wises up.

DiChlor or Trichlor Powdered Chlorine

Dichlor..... and Trichlor.... Chlorine are stabilized forms of granular chlorine.  Trichlor... has a low pH and is slow dissolving, and Dichlor... has a neutral pH and is fast dissolving.  

Both contain cynauric acid as a part of their compound.  This is also know as "stabilizer" as it protects the chlorine in the pool from the degradation effects of UV rays.  Too much stabilizer in the pool water can reduce the effectiveness of the chlorine.  Again, the only means to reduce it, is do DUMP precious water from the pool.

Sodium Hypochlorite

Salt Chlorinator
A "salt water pool" is sanitized with chlorine, regardless of what people are told or think.  Liquid Chlorine (Bleach - Sodium Hypochlorite) is produced at the pool equipment pad, as the salt water passes through electrolytic plates.

This is the same means used to create liquid bleach (sodium hypochlorite).  The only difference is that the chlorine is not injected or poured into the pool, instead it is made within the plumbing.

Sodium hypochlorite has a high pH.  Regardless of what the manufacturers of salt chlorinators say, the chlorine generated has a pH of about 13.  The miniscule amount of sodium hydroxide generated, in no way negates this high pH.  During a week, a pool with salt chlorinators will consume 4-8 times the quantity of acid (to buffer the 13 pH), as a pool utilizing liquid sodium hypochlorite.

Liquid Bleach
Another method to utilize sodium hypochlorite, is to store a barrel of it and meter it into the pool.  It is injected into the plumbing using a peristaltic pump.  Of course an acid solution is also injected to maintain the proper pH.  These peristaltic pumps are best controlled by an ORP/pH Controller (water chemistry controller) that monitors and feeds the chemicals as needed.  Periodic deliveries of liquid chlorine and acid are used to refill the barrels.  This relies upon a reliable local source of liquid bleach and acid.

On-Site Generation
In remote corners of the world, there is no reliable source of liquid chlorine.  Large users of liquid chlorine or remote locations find it economically feasible to manufacture their own liquid chlorine bleach on-site.  The key ingredients are available around the world - electricity, salt and water.  A free standing skid mounted system creates liquid chlorine which is then stored in a large barrel.  This ensures a readily available and steady supply. 

In resorts or hotels, these units are over-sized, so that extra liquid chlorine can be used to mop floors, sanitize showers, clean dishes in the commercial kitchens and to wash laundry.  Since the freight to import cleaning solutions is cost prohibitive, utilizing on-site chlorine bleach become economically feasible and environmentally friendly.

Liquid acid is still utilized to buffer the higher pH.  A water chemistry computer (ORP/pH controller) meters the bleach and acid solution as needed, guaranteeing a perfectly balanced pool, regardless of the weather conditions or bather loads.  Powdered or granular acid can be mixed with water to create acid solutions on site, if local sources of liquid acid are not available.

Paolo Benedetti - Aquatic Artist 
"Creating water as art."™ 
Aquatic Technology Pool and Spa 
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