I became a first-time pool owner when we purchased a home with a pool a couple of months ago. I'm in northern NJ and I hired a pool company to open it 10 days ago(mid-April). It is a 35,000 gal in-ground gunite pool. They put some 3" Tri-chlor tablets into the automatic feeder and 10lbs of Sodium-diclor into the pool as shock and also added an algaecide. The pool has a pressure DE filter. The floor of the pool was covered with a fine silt. I vacuumed and brushed it up several times and the filter required backwashing every day for a week. I was testing for Free Chlorine and was not getting a level so I shocked the pool 2-3 times using Sodium Di-chlor following the package directions (~4lbs per shock). Still very low FC. I brought a sample to a pool store and they found that my Total Chlorine was 7 and Free Chlorine was 0.8. All the other measures were fine (pH, stabilizer, alkalinity, etc.). I have stopped adding chlorine because I think I'm only making the problem worse. The water is looking pretty clear at this point with only a little bit of the silt left. Can you guys provide any advice? Will the Combined Chlorine drop on its own over time or do I need to do a massive addition of Chlorine? Weather is still cool here so we don't plan on swimming for 2-3 weeks. Thanks.