I have 2 Red eared sliders i got them from a friend they were in terrible condition, they had no basking area, they lived in a really small tank with barely no water, they were fed treats which arent suppose to be fed daily. I have no idea how old they are, no idea how big they are, and no idea if their male or female. I took them and they looked pretty healthy i purchased a 10 gallon tank and they have plenty of space to swim. I have a basking area with some default bulbs that came with the aquarium but no UVB/UVA bulb(will be getting soon). I have a water heater with the temp set at 85 degrees, a filter and a thermometer. A few days after i got them i noticed my smaller turtle "Titan" started developing these vertical line going down his Costal Scutes. I would put them together in a different tank that i first got to feed them and they would eat turtle pellets. I then later noticed my bigger RES "Athena(think its a female)" started getting the lines and they look like their in a 45 degree position. I tried scraping it off but the turtles go crazy and i dont want to hurt them.
Here is Titan

And Here is Athena

Please help