Yes, a Red Eared Slider can use this as it is important for their health. Also provide additional heat lamps for basking. Good luck and hope this answers your question! 

Thank you for your question. The amount of lighting you are providing appears to be acceptable though we do recommend keeping the bulbs around 3 feet or more apart. Please be sure that your lighting is mounted so that it isn't shining through glass, glass filters UVB rays.

Unfortunately we do not provide the CRI for these bulbs. More information on these bulbs is available here: http://www.exo-terra.com/en/products/reptile_uvb100.php

Our bulbs are not rated by UVB percentage, however this bulb was formerly the ReptiGlo 5.0 (5% UVB). More information on this bulb is available at the following link: http://www.exo-terra.com/en/products/reptile_uvb100.php

A vertical light bar- go to lighting in Reptiles section. F&S has a vertical light bar. I also have chameleons. But I buy the bulbs made for turtles because they're tougher, and made for the high humidity environments that our chameleons need.

If your tank has lots if branches etc with access to different areas, your babies will seek out what they need. My baby beardie's spiral UVA light broke and it took 4 days for the new one to get here. He had plenty of heat during the wait. When the new bulb was installed. He looked up at it, cocked his head to the side like beardies do, then clambered up the branch to get as close to it as possible. They seem to instinctually know what they need and how to get it. Good luck :o}

yes you can, i definitely use it for two RES