I also live in an area with very hard water. The best decision I ever made for my hair was to buy a water filter that attaches to my shower head. It filters out most of those minerals and softens your water. I can tell a huge difference in my hair ever since I purchased mine and I plan on using one forever.
As for humidity, try playing around with your hair products. Your hair products probably contain silicone which can be good for some hair types and bad for others. Silicones make my hair more frizzy, so I go for products without them. Also, use UV protective sprays to protect your hair from the harsh Florida sun and causing more damage.
To repair the damage that had already happened, you can try Olaplex No. 3. It repairs broken bonds in your hair.
Not sure about testing really but this is the filter I️ was looking at getting on Amazon. Great reviews and it’s not too pricey! https://www.amazon.com/dp/B0752W4WX1/ref=cm_sw_r_cp_api_zVebAb7CQV0JF