Pool chemistry is primarily used for bather safety (to sanitize harmful bacteria) and to also prevent scale and corrosion on pool components.  Pool water must be tested weekly to insure the water is safe to swim and does not contain viruses or bacteria.

Sunlight destroys chlorine and stabilizer (cyanuric acid) is added to pools to protect the chlorine in the water from the UV sunlight.  Adding chlorine tablets each week, without testing the water first, will cause the pool chemistry to have too much stabilizer and become acidic.  Therefore, weekly chemical testing is necessary, and tablets are used on an “as needed” basis.  Heavy use of the pool will also use up the residual chlorine and the water will not have adequate sanitizer to be safe to swim in.  Algae can be promoted to grow in a pool that has low chlorine, high levels of nitrates, high levels of phosphates or has heavy usage.  While algae does not look pleasant, it is not inherently dangerous to a swimmer.  We can test for phosphates and nitrates – there are even products that can remove phosphates from your pool (it does cause the water to become cloudy, even milky white, before the phosphates have been filtered out).  Nitrates however will require the pool the be drained and refilled with uncontaminated water if they are to be removed.

Typically, the white spots are calcium buildup. Too little calcium in the water can, over time, cause the water to “pull” calcium from the pool finish and deposit on the surface.  While all pool finishes will ultimately stain, proper care and chemistry can improve the look of the pool and help the surface last longer.