Kansui powder to Kansui liquid (Koon Chun) conversion?
Google gave me this - which I don't feel in any way qualified to elucidate upon…  

From Omnivore's Cookbook - Kansui (lye water, alkaline solution, 枧水)


  Homemade kansui
  
  Making baked baking soda is easy.
  
  
  Preheat oven to 250 degrees F (120 C). Line a baking tray with aluminium foil.
  Spread baking soda on the foil and bake for 1 hour. The baking soda will lose about one third of its weight and you’ll gain a stronger
  alkali. Do not touch it with your bare hands. It will cause irritation
  to sensitive skin.
  Transfer baked baking soda to an airtight jar to prevent it from absorbing moisture from the air.
  To make an alkaline solution for mooncakes, add 1 teaspoon baked baking soda to 4 teaspoons water; stir to mix well.
  


I'd guess that would give you the made up strength.