I’m going all travertine. FWIW my PB was pretty upfront that flagstone and limestone do the worst with salt. He also said there are sealants out there you can use.What kind of coping do you have? I have flagstone.. and built my pool in 2013 and getting quotes to rip out and replace and trying to figure out what to replace it with.... it could have been just cheap.. but I have had a chlorine pool with flagstone and did not have these issues...love the salt.. have to find something it can play nice with. my friend has travertine and salt and its doing well. Kicking myself for not springing for it at the time it just wasn't in the budget.