Hi RiceVFR, Welcome to the Forum. You obviously have a big decision ahead of you. My first inclination is to tell you to see what the test results are. That being said, depending upon your location and water source, a drain and refill may be a lot cheaper than chemically resurrecting your pool. As far as running the Filter without DE, you will be basically circulating the crud back into the pool. I strongly recommend that you invest in a good quality test kit and learn how to maintain your own pool and save yourself money from highering a Pool Service.