The problem with slugs is that they destroy the roots as well as the leaves. According to Jorge Cervantes, one measure you can do to prevent slugs from your grow is to place a salty beach sand around your garden, 2-6 inches wide to prevent them from passing.
Some things he recommends doing is to place a board in the garden which they will seek refuge under. Pick up the board and kill them. You can also buy bait at your grow shop or garden center and make a slug hotel out of a covered plastic container. Cut a hole 1x2" in the container and place the bait in the container.
You may want to replant at this point since your grow is so young. I would start with a new pot and some good soil, not from the ground. Then place the sand around the perimeter of your pot to prevent any slugs returning. Good luck.