Hi there, welcome to the forums!
I used the Basic GARF recipe with a little less cement and added sand and Water Softener Salt instead of Driveway salt.
I did that because the Softener salt is fit for human consumption, so i figured its more fish safe.
Here is some links to threads on here
My Build thread
MMLR
More with pics
Reefer Rob's tank has some nice DIY rock and links to his pics are on the MMLR thread, 3rd page