Pond foam

[Mr Cob]

another note...don't let the foam bubble up otherwise you get poop looking foam walls. Poke it when it bubbles up and move the foam around with a stick and I promise it will look more realistic when it dries..sprinkle some aragonite on it while still wet to really give it the rock texture.

DO let it bubble up if you want to be able to mount frag plugs to it easily. I did that in a few areas on the bottom.