Everybody is familiar with glass. Balustrading or Pool glass is much the same as window glass, except it is always toughened glass.
Toughened glass is cleaned the same way window glass is cleaned, normally best with clean (grit free) water, and a squeegee.
Toughened glass is difficult to break with a blow directly on the face of the glass, however should you strike toughened glass on the edges it is a different matter. The toughening process results in stresses on the edges of the glass. If you knock or strike the edges of toughened glass with a hard object (like a stubby bottle), you may release these stresses resulting in the glass breaking into a million little pieces, which is why it is called safety glass.
Stainless steels need to be cleaned for aesthetic considerations and to preserve corrosion resistance. Stainless steel is protected from corrosion by a thin layer of chromium oxide. Oxygen from the atmosphere combines with the chromium in the stainless steel to form this passive chromium oxide film that protects from further corrosion. Any contamination of the surface by dirt, or other material, hinders this passivation process and traps corrosive agents, reducing corrosion protection.
Clean fresh water is a good cleaning agent for stainless. The stainless steel polishes are often just a mineral oil based product, when applied leaves an oily residue which gives a short term measure of protection.
Tea staining on stainless steel occurs when impurities and polutants on the surface of the stainless discolour to form a gold or brown colour. Provided the colour does not deepen to a dark red brown (this is corrosion), the tea staining can be removed. You should probably seek professional help, however tea staining can be removed with a passivating gel. Once applied it can be removed an hour or so later and it will remove the majority of tea staining as well as rebuild the chromium oxide layer and restore the lustre of the stainless steel.
When purchasing your stainless steel balustrading or pool fence remember the best protection against "tea staining" is to buy mirror finished stainless.