In the British Isles, soft water is common in Scotland, Wales, the extreme SW of England and parts of Ireland. The pH can be rather unstable in soft water areas, but alkaline chlorine donors such as calcium hypochlorite will help to increase hardness as will the addition of calcium chloride. The purpose of shock dosing is to overcome a problem such as algae growth or unpleasant chlorine smells. It does this by satisfying chlorine demand i.e. by killing bacteria, algae, and other micro-organisms, and breaking down accumulated organic impurities to leave a chlorine residual. Never mix concentrated chlorines in the dry state.
Total alkalinity is a measure of the amount of alkaline materials in the water.
This alkalinity will usually be present as bicarbonates, but with a very high pH carbonates and hydroxides can be present as well. It would require a much greater force if the sphere had the bulk density of a cannon ball. In this example, the increase in bulk density between the balloon and the cannon ball is analogous to an increase in alkalinity. The increase in force required to move the balloon and the cannon ball is analogous to the idea of increased 'buffering'. It is important to create the correct amount of buffering in the pool such that the pH can be adjusted if necessary but rapid fluctuations are prevented.