Chris, I frag zoo's every week. the best thing that I have found is an exacto knife. I take them out of the tank in a bucket of water. agitate the zoos so they all close up. if you can cut a frag from the center of the colony that works the best. they grow back quicker. I would recommend taking small frags no more than 5-7 polyps at a time. the smaller the frag the quicker the frag grows. just cut along the matting and wedge the knife under the zoo and try and get a bit of rubble with them. let me know if you need any more help.