They will come off when the scuts are shed on a normal basis. Of course that will come back again if the water is still as hard, and he is basking under a lamp. It is just an aesthetic problem I would not worry too much about it
He was in bad condition when I got him but coud not leave him in the state he was in the pet shop, but now I think he might have a bit of shell rot. How do you teat shell rot?
That is defintely a Reeve's turtle, Mauremys reevesii
Care is almost idetical to a North American spotted turtle. They are not the best swimmers and water about 1-1/2 to 2 times their shell length is best. They do need a basking spot with basking light as they are active baskers. They are quite hardy and do well on commercial pellets.
Just a update. As I was told to get Povidone-Iodine for shell rot but as I live in the UK and the Iodine is band in the UK, what else can I use instead?