Keep the pump running 24/7, your FC should come down pretty quickly since you weren't able to deep clean the sand yet (you're prob ok there)An update - so last night I:
Clearly I got something wrong which made the amount of chlorine added way too much. I did the chem tests a couple times to be sure, and the pool volume I could be off by ~2000 max I calculate.
- backwashed the filter taking psi from 20 to 16 (but didn't deep clean, was too worried I'd bork the system)
- added 3 gallons liquid 12.5% sodium hypochlorite to get to 20 SLAM level (per Pool Math I needed .5 gallons more, but I wanted to be conservative, funny considering results below)
- brushed pool, left pump running
- tested 2 hrs later and free chlorine was 31 (!)
- I tested early this morning (7 hours later) and FC was 29
- pool looks slightly more blue/clear this morning, and I just brushed it
Reading about what to do if FC is too high I'm seeing that I should probably let it settle on it's own as there aren't great ways to get it down quickly and it's not terrible. Next 4 days are going to be very hot and sunny, so it should go down. Will test FC again in a couple hours and post back.
What are the actual measurements of your pool? (length/width, max depth, min depth?)