I agree with them, using something under the hill to give it umph, and not dirt.
the issues with mounding miracle grow dirt is that it wants to float, and even if you slowly add water to the tank, itll bubble up and crumble, I've had first hand experience. It took me nearly a week to clean up the mess after that.
Once the hill is built and as you cap it with sand, you can take plastic pieces to hold the hill up. Something with flat/strong/plastic sides, like a fiji water bottle. cut each side of the bottle into a hill holder, and cut to the length you like. you can place them length wise and shallow, or straight down. doing the latter you can place the pieces where you want as you lay the foundation of the hill.
kind of like that where the @ is the foundation of the hill and the | is the plastic holder. s is the sand.
let me know if that doesnt make sense
Last edited by Nestle_; 10-14-2013 at 09:19 PM.