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Pool Care and Maintenance

Instrumentation in swimming pools requires the continuous control of the ORP/REDOX potential and of pH while keeping the pool clean and periodically adjusting pH buffers and occasionally cleaning the filters, replacing the water and shocking. Instruments Australia supply instruments for measuring and controlling pH and ORP/REDOX.

Swimming pool owners want pools to be low maintenance, clean, safe and healthy.

How big is your pool

Chemical Safety Tips - Handling and storage

To determine amounts and types of chemical required, your pool should be tested daily for pH and free chlorine; and periodically for alkalinity, stabilizer, and hardness.

Proper maintenance of pools and spas requires:-


Available chemical treatments can:

Chlorine will sanitize and oxidise but needs protection from UV light.

Chlorine produces Hypochlorous acid (HOCl) in water

  1. HOCl dissociates (breaks up) HOCl < == > (H+) and the hypochlorite ion (OCl-).
  2. HOCl reacts with bacteria and organics. HOCl is a very effective sanitizer
  3. OCl- reacts with ammonia (NH3). OCl- is an extremely strong oxidizer
  4. HOCl reacts with sunlight and needs to be stabilized with Cyanuric Acid
  5. Chloramines formed from reaction with ammonia are unpleasant and smelly.
  6. Chlorine compounds change pH which then need adjustment.
  7. Some chlorine compounds change water hardness
  8. Some chlorine compounds include cyanuric acid - regular pool draining required.
  9. The total dissolved solids (TDS) of an average pool is increased
  10. Chlorine is the most popular sanitizer chemical

Chlorine can be made locally at the pool by electrolysis

Salt in Water with electricity will produce Chlorine + Caustic Soda + Hydrogen

The total Chemistry is: 2NaCl + H2O = CL2 + 2NaOH + H2

Bromine will sanitize and oxidise.

Bromine produces Hypobromous acid in pools and spas

  1. HOBr dissociates (breaks up) HOBr < == > (H+) and the hypochlorite ion (OBr-).
  2. HOBr reacts with bacteria and organics. HOBr is a very effective sanitizer
  3. OBr- oxidizes ammonia into Bromamines which are active sanitizers,
  4. HOBr reacts with sunlight, it lasts longer but can not be protected.
  5. Bromide can be oxidized back into hypobromous acid with a strong oxidizer.
  6. Bromide compounds change pH which then need adjustment.
  7. The >total dissolved solids (TDS) of an average pool is increased

Shock Treating / Super Chlorinating

Shock treatments should be done once a week during peak season when temperatures and bather load are heavy. Cloudiness and/or strong chlorine odors are indications that a shock treatment is needed. Shock treatment is the "burning up of pollutants with a strong oxidizing chemical". Incorrect amounts of chlorine used will cause problems. Not enough will raise the level of eye burn and skin irritation because the level of combined chlorine compounds is increased. Too much chlorine will take days to drop to safe levels.

Non-chlorine shock products like potassium peroxymonosulfate, also known as permonosulfate solve these problems. Like chlorine, permonosulfate is an oxidizer that will destroy organic contaminants such as ammonia in swimming pools and spas. Permonosulfate compounds do not kill or disinfect. Permonosulfate reacts directly with the ammonia and chloramines to produce chloride ions and nitrogen. Swimming can be resumed after the permonosulfate has had a chance to dissipate, usually in just a few minutes.

Ozone Gas

Ozone is a gas (chemical formula O3) that is one of the strongest oxidizers and disinfectants available. It is stronger than chlorine, bromine, hydrogen peroxide and hypochlorous acid.

Ozone is produced in a corona discharge. Air passing through an electrically sparking chamber produces ozone from oxygen. Air passed close to one or more Ultraviolet lamps will produce ozone from oxygen.

Comparisons Bromine vs. Chlorine

There are some significant differences between Chlorine and Bromine as sanitizers. Chlorine requires superchlorination to remove unpleasant chloramides, bromine doesn't. Bromine can be regenerated using a strong oxidiser, chlorine can not.

Copper and Silver Ion Generators
Copper ions in water will inhibit algae growth and Silver ions kill bacteria.

Ultraviolet Light will Sanitize
UV Light at the right wave length kills bacteria and algae but not viruses.

Oxidizer and Chlorine Summary

How much sanitizer product do we need to purchase to achieve the right amount of active chlorine? Use this chart to calculate the best priced options.

Algaecides and Enzyme Sanitizers

A range of compounds will "poison" bacteria and algae.


Once the chlorine level is allowed to drop below 1.0 ppm, unsightly algae may appear. Algae can discolor water and give off unpleasant odors. This condition may also be an indication of improper sanitation. Should this problem occur, consult your professional pool dealer.


pH is the scale of measurement of acidity or alkalinity in aqueous solutions. A neutral solution such as pure water has a pH of 7. Solutions with a lower pH are termed acidic and solutions with a higher pH are termed alkaline. pH ranges from highly acidic pH 0 to highly alkaline pH 14. The pH of the human eye is about 7.5. Under normal conditions, it has been found that the proper pH for pool water is approximately 7.5 with pH 7.2-7.8 being an acceptable range.

Water Balance

Balanced water is a term used to describe an ideal condition of pool water. Water is "Balanced" if it contains just the right amount of pH, pH Buffers, Calcium and Magnesium Hardness and dissolved solids. Water high in hardness can become cloudy and Scale the insides of pipes restricting water flow. It can cause calcification of sand in filters, reducing their efficiency. Scale can also discolor a pool's interior. Low hardness and unbalanced water can contribute to corrosive water conditions. A certain amount of hardness is desirable. The desired range is between 100-400 ppm. Once again, your water should be tested periodically for hardness. Some minerals such as iron and copper can stain your pool.

Buffering (sometimes referred to as Total Alkalinity by pool people)

Buffering represents the amount of generally alkaline minerals in water that act as a pH buffer. It is the measure of the buffering capacity or resistance to a change in pH of water. These chemicals minimize changes in pH, making pH easier to control. The proper buffer range is from 80 to120 ppm.

In Summary

1. Opening Your Pool

2. During the Swim Season

3. Closing Your Pool

Prepared by Trevor Croll,

42 Pearse Street, Keperra, Queensland Australia, 4054.
Phone 61 7 3855 1115