I've been going through the FAS/DPD test like crazy, trying to hold the pool at shock level until SLAM is complete. I have a CYA of about 40, which (in regular conditions) gives a recommended FC=5. Most of the quick & cheap chlorine testers (Tayor K1000) don't give real good resolution. I was reading in another post that people like to go 1-2 ppm over recommended at night so the FC holds through the next day. Does this leave the FAS/DPD test as the only daily option for measuring 6-7 ppm? Or do you just approximate how deep into the 5-10 range the reading is (is this even possible)? I'm new to the pool thing, so maybe there becomes a pattern to how much chlorine is lost per day.