Well I have a 60 hex tank with GS on it. I do not use a lot of live plants and this tank doesn't have any in it. What I did is evenly coated the glass with the GS and allowed it to expand. Be careful not to apply to much as it will keep expanding and you will not have the results you want. I usually place Pete Moss on top of this as a final layer. If you are talented with this stuff you can make all sorts of sloping areas areas and multi-levels, but when I have a chance to post my pictures and what not you will see I like easy to clean and I don't care to show off either.
