Buy a copy of AC Highfield's book, "Practical Encyclopedia of Keeping and Breeding Tortoises and Freshwater Turtles.
Highfield recommends and I have followed successfully the following for intestinal parasites. Use panacur paste at a dosing rate of 50 mg/kg of total body weight. You will need to calculate the dosing rate based on the strength of the Panacur Paste, 10%?, 5%?. Mix the measured amount of paste in with the food. Repeat in 14 days.