EZR,

(DADGAD) is a different and separate tuning from Open D.

For Open D, you want:

6th string = D
5th string = A
4th string = D
3rd string = F# (one semi tone down from the existng G)
2nd string = A (one whole tone down from the existing B)
1st string = D (one whole tone down from the existing E)

Hope this helps.