Other pool chemicals
The greatest use of chemical products is in the bactericidal treatment of pool water. Many special conditions, however, create requirements for additional chemical treatment.
Flocculants
Aluminum sulfate (Al2(SO4)3), commonly called alum, is used as a filter aid and as a coagulant and settling agent for water turbidity. Alum “floc’ is a white, gelatinous substance that attaches to free-floating matter in water to form larger, heavier-than water particles, which settle to the bottom of the pool. Alum floc is especially effective on sand filter beds. The floc partially fills the voids in the sand bed and holds organic debris in its suspended gelatinous coating.
Alum is introduced as a filter aid at the most convenient entry point ahead of the filter. The chemical feed, hair and lint strainer or skimmer are effective points of introduction. However, to coagulate particles in pool water, a powdered alum is broadcast over the pool surface at the rate of two ounces per square foot of surface area and is permitted to stand overnight or for a minimum of two hours. After standing, the pool should be vacuumed with minimal agitation to prevent the floc from breaking apart. It is recommended when using alum as a water clarifier or a filter floc that the pool water be adjusted to pH of 7.6-7.8.
Flocculants aids, with a combination of ingredients, sold under various trade names, have been used to produce a heavier or more stable floc. Colloidal silica, a clay called bentonite and a new family of organic polyelectrolytes are available.
Chelating or Sequestering Agents
Many stains around main drains and inlets have to be cleaned by hand, but the stains can be kept from returning. Sequestering agents increase the ability of water to hold metals in solution instead of precipitating out to form stains. Chelating agents remove iron and other metals from the water and the pool walls. Pools with high iron content use a chelating agent as part of routine water treatment.
Degreasers
There are commercial acids and biodegradable detergents that effectively clean D.E. filter bags and filter sand. Each product has its own ability to degrease and rejuvenate filters. Each filter system has its own individual solution for doing the job.
Defoamers
Foam or suds is a chronic problem for most spas. Occasionally, a box of detergent is thrown into the water as a prank, and a defoamer made specifically for pools and spas is necessary to remove the foam. A bottle of defoamer is handy to have on hand as a safeguard.
