Reduction: What is a reduction?

Answer: The reversal of an oxidation, i.e. a return to a neutral and stable form.

Total Dissolved Solids: What is meant by that?

Answer: It refers to conductive ionic matter in water. The problem with a description for TDS is that something that is totally dissolved cannot possibly be a solid. A more accurate description such as ions would be an improvement. A further problem is that other uncharged matter may also be dissolved, such as sugar or salt crystals, but no mention is made of that.

Ultraviolet: Is ultraviolet invisible?  

Answer: Yes, Ultraviolet at 397nm as well as infrared at 700nm are beyond human visions normally. Some birds and animals however can perceive some of these shorter and longer wavelengths. Many modern spectrophotometers identified as UV/VIS have an observation range from 200nm to 700 to 1,000nm (I micron). All Ultraviolet light is considered dangerous for the eyes and skin. The shorter the wavelength however the more UV is unable to penetrate,  firstly acrylics, ordinary glass and then pure quartz at 200nm beyond 200nm and shorter, even water molecules and the air will block UV and can only traverse through a vacuum, i.e.  ‘Vacuum UV’.

Violet and Indigo spectral colours: Why are these two words largely ignored?

Answer: Many people only perceive these two spectral colours at the shortest wavelengths and bottom end of visible light as blue or dark blue. Some people are not able to see them at all and treat them as ultraviolet light starting below 400nm, such as 397nm. 

Water Purity: How do we address water purity?

Answer: With water being considered to be the greatest solvent we know of, it becomes obvious that over time water is likely to contain a great deal of chemistry, ionic materials, salts as well as uncharged organic and inorganic matter. To consider hazardous content being organic or inorganic in origin and secondly substances that are not hazardous but nevertheless unwanted. Water purity is a relative concept that defies understanding except for appropriate testing for the different properties of water. These may be defined as ionic content, organic content, inorganic content and the level of foreign content not otherwise specified. Generally speaking vested industries are only interested in very specific content in water. A consumer of water would definitely have a more personal interest in water purity.

Zeta potential: What is a Zeta potential?

Answer: A Zeta potential is an interfacial static electrical charge between water and most metals, in particular silver. This electrical charge has a mutually repelling action that is Zero at the Iso-electric point, around minus 25mV where it is a level to overcome the attraction of the Van der Waals Force and able to increase to as high as minus 100mV.