I used plain gravel with 22oz. of laterite mixed into the bottom third: 55oz. seems a bit much to me, and I doubt you need it with the laterite. The plants have only been in for a few days, but, so far, they seem to be doing fine.and for substrate my plans are to use seachems black flourite as a main substrate,and my plan was to mix in a 55oz. box of pure laterite,now i do not think it would do anything.. will it??