Not losing chlorine

[Conehead396]

I switched my pool over to a SWG last week (Aqua Trol). I ran it for a few days and took my water in to have it tested for a baseline.
Pool is 24 X 52 above ground.

FC 4.8
TC 4.9
PF 7.3
Calcium 280
TA 20 (9added 5 lbs alk up)
CYA 15 (added 6 lbs)
Salt 3300
Water looks good.

This was on Thursday. We have almost 4 inches of rain from then to Sat. morning. I turned the run time down on the SWG and ended up cutting it completely off as the pool actually ran over from the rain. Sun came out Sat afternoon, and all day Sunday and today. Chlorine is still high wit OT test. I am going to get it rechecked at the store tomorrow. Before the salt switch I would lose my chlorine in one sunny day.

Any ideas why it is holding so high over four days with no chlorine addition.

I have already ordered the TF100 kit suggested here.