Why would it be important to maintain a water hardness level in a small vinyl swimming pool?

Answer 1

I don't know that you need 'hardness' per se. What I think you are referring to is total alkalinity which is usually expressed as ppm CO3 (parts per million carbonate which is also how water hardness is usually expressed). The alkalinity is a water buffer that allows you to keep control of the pH and chlorine levels of the water more easily. If there is no buffer solution then the pH of the pool can vary quite a bit which uses up the added chlorine very quickly.

If you aren't trying to maintain the pH and chlorine levels then the alkalinity of pool shouldn't really matter.

Hope that was helpful.

Answer 2

to keep it fresh so it doesnt make your skin dry so it dont hurt the pool