In your warm climate I would recommend a sedum such as the blooming ice plant and like most sedums this ground cover is grown more easily by cuttings rather than seed. Space young plants one foot apart and you will get good coverage in a season. You do need to visit a local nursery however as they will be able to tell you which plants can become invasive in your climate and which groundcovers to avoid. Creeping phlox may not be the answer if you have hot and humid summers as it is susceptible to mildew.  Another suggestion is to talk to the pool maintenance people in your area. They will be able to suggest the best plants for around a pool that do not cause problems with litter in the pool filter. If you really want to plant from seed than a lawn planted with grass seed would be the most practical groundcover. Keep growing, Marianne Binetti