You should be feeding your 6 months old turtle the amount of pellets that can fit
inside its head, excluding the neck, daily. Just guesstimate the amount, it doesn't
have to be the exact volume.
For better overall health, offer veggies daily.
The turtle will lose weight once you start feeding the correct amount, but it'll likely
take quite a while.
Please read more from the main site. You can start here:
http://www.redearslider.com/pellets.html