Chen,
What is your CYA level?? Without knowing your current CYA, no one can tell if your FC (chlorine) is ok or too high or too low..
See the saltwater section of this link..
FC/CYA Levels
We are different than most pool stores or pool websites.. We use science and testing to determine if our pool water is in balance.
This time a year, I would say 85% output is way too high..
It could be your CYA is way too low allowing the sun to quickly burn off your FC.
It could also be that you have algae (even if you can't see it yet), which is consuming all the chlorine that your salt system can produce.
Show us the following test data...
FC
CC
pH
TA
CH
CYA
Salt
Thanks,
Jim R.