Your burning up 6.5ppm fc in 10 hours? How many gallons is the pool?
What's the width amd length of the pool and how deep? I asked because that's extreme FC usage even for current weather. You have something brewing. Jump back to slam levels before you end up with cloudy water in the next days
Looks like u caught it in the nick of time. Are u sure your chlorine is fresh?
Try again in a few. That doesn't sound right. I don't think you can burn through that much chlorine in 30 minutes. Rethink how much you added and how many gallons you have to work with. Other than testing error it sounds like you have the wrong pool size. How much / what did you add?