ACS 5-Year Data for Age Range Population & School Enrollment

I'm looking at the 5-year estimate data for a specific zip code and analyzing population by age. Specifically, I'm looking at the population changes in the 0-4 year old and 5-9 year old populations. The analysis that I'm attempting to complete is comparing this data to elementary school enrollment. The elementary schools are almost exclusively fed from the zip code that I am analyzing. My question is basically how accurate you feel that the population count for a given zip code. If it helps, the zip code in question has a total population of approximately 20,000 (up from approximately 14,000 over the past 10 years). I'm a bit new to the ACS dataset and would like to avoid being a statistic of the Dunning-Kruger effect! Slight smile