I/8th rule..do you mean only pour about that deep in inches each layer?
Make sure your water course is completely sealed...no holes or gaps.
You can, and should, tint the first couple of layers. Often a single drop of paint will do. Choose a medium green, something a little yellowish. Only a single drop, maybe try a half-drop first. If you want some turbidity or opacity, add a 1/8 tsp of plaster of paris powder.
To get the ripples, wait until the pour is getting harder, and then use a wooden dowel end to shove the surface, prod it, and try to get some peaks. This will take some time to place the dowel end randomly, firmly and carefully apply pressure enough to deform the surface, and then select another spot. You may have to return inside of minutes to repeat is the pour is not sufficiently hard. At some point, the surface will remain knobby.
