Welcome to the forum... I hate to tell you, but a ten gallon tank is already too small for two RES. The minimum tank size is 10 gallons per inch of turtle. The smallest tank that you should keep two RES in is a 20 gallon.
I might be mistaken but it doesn't sound like a tank tank, but more like a death bowl. If it it, scrap it immediately and get them into a regular tank where you can set up a regular basking area that will allow you to have a higher water level, the proper lighting (heat bulb and a UVB bulb over the basking area), a heater, a filter rated 3x's the tank size, the correct basking and water temps, etc. Their environment is extremely important to their well being.
I suggest reading through the forum and main site for lots of great info on raising happy, healthy RES.
