Rust Stains from your tie wire or rebar inside the pool shell will only get bigger after a while. Resurfacing the entire pool is the only way to get a consistent, stain-free search for the pool surface area. Cracks absolutely are a positive sign you possibly have or should have https://www.google.com/maps/place/Griffin+Dynasty+Pools+%26+Pavers/@27.260973,-80.4533593,10z/data=!4m6!3m5!1s0x8eadd681600ed435:0xc2531cf82534e327!8m2!3d27.260973!4d-80.2885644!16s%2Fg%2F11v_4jn4x8?hl=en&entry=ttu