Which chemical is used to raise alkalinity but requires the most maintenance?

• A. Lime
• B. Soda ash
• C. Sodium bicarbonate
• D. Calcium hydroxide

Answer: (A)

Raising alkalinity means adding a base that forms hydroxide and carbonate species to buffer acids. Lime does this very effectively, providing a large increase in alkalinity (and pH) per unit dose and also adding calcium hardness. That strength comes with a higher maintenance burden: lime is fed as a slurry, so you need a lime slaker and dedicated handling equipment, plus careful dosing and thorough mixing to keep the slurry uniform. Lime can cause rapid pH changes and promote calcium carbonate precipitation, which leads to scaling and fouling in pipes and equipment, requiring regular monitoring, cleaning, and maintenance of feed systems. Because of these handling and scaling considerations, lime generally requires more maintenance than other alkalinity-raising options like soda ash or sodium bicarbonate, which are easier to feed and manage. Calcium hydroxide is essentially lime in another form and carries similar maintenance needs, reinforcing why lime sits at the higher end for upkeep.