I have a ledge in my tank that I was putting gravel on and a plant. But its hard to get enough gravel over the base of the plant to hold it firmly(because the ledge is smal and the gravel tends to fall off). I just thought it would be easier to secure it first then lay the gravel around it. Plus I have some air tubing I needed to secure. I just didnt know what was safe for the aquaruim.