I am no expert, this being my second year of pool ownership. I use one pool supply store for my water tests and supplies. Leslie's Pool. My local store is awesome. I don't buy chemicals at big box stores, or at least I have not yet. I buy where I go to for answers if I have a question. I needed 30 pounds, to correct the hardness. I understand the pump etc. will last longer if correct, Ive had a hot tub for 15 years, same idea. Good luck.

Yes if you don't add it it will take it from your white goods or your liner itself....some will say no but look at your liner manufactures recommended chemical levels as it applies to your warranty