I would not recommend sand , get something coarser , at a minimum coarse sand . but yeah succulents don ' t need or really want too much organic soil . the reason water just sat on top was because it contained too much peat , which is terrible for succulents , as it becomes hydrophobic when it dries out , and you want your soil to dry out with succulents , it can be solved by completely submerging the pot not the plant in a bucket of water for a minute and then letting it drain , but it will become hydrophobic again when it dries out , so it ' s better to avoid peat and use more inorganic material . some of the mixes used in rbonsai should be very suitable for succulents tbh . as for being planted close together , plants adapt to their surroundings , and as long as they don ' t get too wet and rot they should be fine . EDIT number one , most important tip make sure your soil drains well , and make sure the pot has holes for the water to drain out of , water in the bottom is what will kill a succulent .