Hello, we're preparing to excavate a 2' deep hole for our new AGP. We will be installing the columns on dug-in concrete pavers then laying down fine mason sand then a pad. Does anyone have recommended procedure/product for Nut Grass killer to be used under the sand; or is it not necessary? I was thinking of using a general purpose granular grass/weed killer. Also, should I apply a fungicide to the sand to prevent liner staining; if so, what type? Thanks for any input.