Geralyn, try it with two Gratz springs first. If you can't move the carriage, of course back off to one spring and begin with a small range of motion until you know you can control the carriage. I work out with Meredith regularly and she typically uses one red spring which is medium to light resistance given the exercise. Meredith is also pretty light (though strong) herself, so that comparison would play a role in what spring you choose as well. Good Luck!
One of my favorite reformer workouts on this site so far :) Loved all the flexion focus! Also as stated by several others the break-down of the snake...can't wait to try!
That was such fun, Meredith! Enjoyed the side lying hip work, as well as the undulating Thigh Stretch...and the prep work for Snake was excellent...thank you!