Rivulose

I'm getting rising Reallocated sector counts ~57208 on one of my drives so I bought 2 identical 12TB refurbs to a) replace the dying drive b) increase the array size. Preclear on both these new drives just finished and I was going to start parity rebuild on the replacement but when I try to assign the replacement drive it comes up with an error and wont let me start the array. Under the HDD identification it just says "wrong" The replacement is "12tb" but byte size is showing 11.9 whereas the dying drive shows 12tb. Whatre my options here to get this going? 2 12TB Parity Drives 1 1TB Cache 6 12TB Array Drive 1 3TB Array 2 12TB Precleared disks Thanks