Chlorine

• Liquid chlorine
  
  Chlorine is used for septic purposes. There are different kinds of chlorine to use. Sodium hypochlorite (liquid chlorine) has low cost, instant effects and short shelf life, but has high salt content and dissipates quickly in sunlight. Elemental gas chlorine is the least expensive and has no additives; on the other hand it is very unstable and needs EPS and DOT licenses. Dichlor, which comes in tablets, has good protection from sunlight, dissolves quickly and leaves no residue. Choosing the right type of chlorine will depend on your specific needs.
  To decrease chlorine, use a chlorine neutralizer.
  
  

pH

• Chlorine tablets for chlorinator
  
  There are a number of factors that can change pH levels but there are chemicals that can directly affect this compound. Soda ash (sodium carbonate) is used to raise pH levels while dry acid (sodium bisulfate) is used to lower them.
  
  

Alkalinity

• Baking soda
  
  Alkalinity is used as a "buffer" for pH levels and is the first thing you want to adjust when pH is off. To increase alkalinity, add granular sodium bicarbonate (baking soda). To decrease alkalinity, add muriatic acid or dry acid. Note: the amount of chemicals to add depends on the volume of water and the amount of variance in each of the levels. Testing kits and chemical tables make things very easy.
  
  

Calcium hardness

• Calcium chloride flakes
  
  Raise levels of calcium hardness by using calcium chloride. To decrease, partially drain the water and add fresh water.
  
  

Other chemical products

• Chlorinator
  
  There are a variety of different chemical processes that have been developed to affect hot tub water. Some of these include water clarifiers, algae killers, chlorine neutralizer, and organic chlorine enhancers.
  Other products to consider using are chlorinators and testing kits. Chlorinators are connected to external piping to inject tablet chlorine into the water steadily. A testing kit will help you determine how to maintain the chemical levels in your hot tub.
  
  

Warnings

• Be careful when handling chlorine; it can stain clothes and burn your eyes. Never add water to chemicals; only add chemicals to water. Different types of chlorine affect pH differently, raising it, lowering it, or having no effect at all.