I have this spacing above my pool tile and under the coping. Some of the tiles around there are loose. Most of the pool is fine, but there are four sections (about 6"-24" each) where it is separated like this. I really knew nothing about pools a couple of months ago, but I've been trying to educate myself. What should I do to repair this? I'm assuming I need to fill in that space. Can I just use sanded grout or an epoxy grout? I'm very handy and usually diy fix just about everything. Any help is appreciated. Thanks!