Last year outdoors i had some seven gallon grow bags in the swamp. We had a really dry year. Luckily it was a good year for the beavers, so i had about an acre of land that was covered with about six inches of water. I took the seven gallon bags and set them directly in the water. They worked almost exactly like a ppk. The only difference is they only got top watered about once a week. The top half of the bags were always dry, and the plants loved it. I put them out in the beginning of july and got an average of 100 grams per plant. happy frog is actually more coarse than coco. With the perlite in it, i think it wil work for a ppk. In my experience happy frog is an airy medium, it's gonna work. If it doesn't i'm gonna hold a gun to it's head till it does.I don't think pure happy frog will work... it will need to be cut for air porosity otherwise it will waterlog and die as I and Dave the Newbie have experienced with fine coco. I do like the idea of soil PPK though for guerilla growing. Give it a whirl Franky, let us know how it works out.