Ok today Tilly passed a pinkish substance from her bottom, it's usually white, y'know the chalky substance they pass, is it abnormal to be pink?

It can happen, make sure its well hydrated.

I had the same problem with one of mine yesterday. Does anyone know what causes this I'm sure the hydration is ok cos she climbs in and out of the water at least once a day, usually leaving a deposit to provei t!