Water needs to be clean and hygienic. The removal of suspended solid matter from the spa water is done by the spa filter, but the hygiene of the spa is controlled by the chemicals and pH. It is most important to maintain correct dosage levels and pH values as apart from hygiene considerations, excessive acidity and residual chlorine levels may eventually attack the pigment within the acrylic surface, ultimately causing discoloration or bleaching.
Recommended sanitizer chemicals to be used in the spa are either chlorine or bromine tablets. The chlorine comes in the form of white 20 g trichloroisocyanuric acid spa tablets, (not 190 g swimming pool tablets), and the bromine in the form of 12,5 g bromochlorodimethylhydantoin tablets. Neither tablet should be allowed to come into direct contact with acrylic surface, since bleaching may occur. Such bleaching is permanent. It is suggested that they be floated in a container on the water surface. Bromine is also available in a floating dispenser.
Dosage is about one tablet per week, but this is highly dependent on spa usage. Residual chlorine should not be more than 1-2 PPM and should be checked to ensure excessive levels do not build up. Bromine tablets are not as pH dependant as chlorine, and may be used if the user is allergic to chlorine.
This is arguably the most important aspect of spa hygiene. PH should be checked and corrected on a regular basis. Ideal pH range is 7,2 to 7,6. A pH below seven is acidic, and above seven is alkaline. Seven is neutral. Acidic pH will result in corrosive water, a sour smell, and irritation of the eyes and skin. Alkaline pH may also irritate the skin, and may promote algae growth in warm water.
Trichloroisocyanuric acid tablets slowly lower the pH, and this should be countered by the addition of small doses of sodium bicarbonate or Soda Ash… Covered unused spas may over time build up both acidity and chlorine levels if left filled and tablets added frequently. If left unchecked, such conditions may eventually lead to bleaching of the spa surface. Such bleaching is permanent.
Ideal spa water temperature is: summer 32°Celcius; winter 36°Celcius. Never allow the spa water temperature to exceed 40°Celcius.
Do NOT use pool chemicals in a spa. Chemicals such as hydrochloric acid (pool acid), sulphuric acid and dry granular calcium hypochlorite may damage or bleach the spa. Such bleaching is permanent.
Use only specified fragrances purchased from a spa dealer. Do NOT use ordinary bath salts in a spa.
Do NOT use abrasive cleaners, bleach, solvents, or any other strong chemicals to a clean a spa. The use of solvent may not only damage the acrylic surface, but may also depassivate the surface, allowing dyestuffs from cleaning agents and fabrics to stain the surface.
Depending upon use, the spa water should be replaced every 30 to 90 days. If a spa is to be unused for a period, it should rather be drained and left empty.
Heating up the spa
The increase in water temperature depends on various factors. The most common error is to expect to feel hot water coming from the jets just after switching on the spa. It is rather a slow heating process (trickle and charge) due to the amount of water involved. Think about the time it takes to heat up your geyser. Your geyser normally holds about 200 liters of water where your spa, depending on the type, could easily hold between 800 to 2500 liters of water.
The time to heat up the spa depends on various factors:
a. The more water , the longer it will take to heat up the spa.
b. The size of the element. A 4Kw heating element will take approximately half the time to heat up the same amount of water than a 2Kw heater. To be able to run from a house plug, the plug-and-play (special) spas come fitted with a 2Kw heater. Should you require a 4Kw heating element, the wiring in the control box will have to be changed and because the load will exceed that of a house plug, a thicker cable needs to be installed from your main distribution board.
c. Most heat is lost to radiation from the surface of the water. This lost heat can mostly be retained by using a tub cover. The following example can be given though it could still depend on other factors:
Let us suppose the water temperature was 36°Celcius when we switched the spa off in the evening. With a cover you could expect to find the temperature above 30°Celcius the next morning. Without the cover the you could expect the water to be close to tap temperature.
Use a thermometer to read the increase in water temperature. As it is a slow process, it is almost impossible to feel the increase in temperature from one hour to the next, especially if the water temperature is less than 30°Celcius.
To give some idea of the time involved to heat up the spa let us consider the following example:
Say you want to heat up the spa to 36°Celcius. The current water temperature is 16°Celcius. Spa capacity = 1000 liters
Subtract 36 - 20 = 16°Celcius
With a 2Kw heater it should take about 16 ÷ 2 = ±8 hours
A 4Kw heating element should take about half the time 16 ÷ 4 = ±4 hours