You have 3.5ppm combined chlorine. There is no purpose in doing an OCLT.
You need to shock your pool. Please read the information about shocking your pool, in pool school. Please... if you don't go read up on that we can not help you. There's too much information that you need to know, and it's all written down in pool school for you. We can help, but if you don't digest at least some basics everyone's time is wasted going round and round asking you to shock the pool that never gets shocked. Nothing gets solved and your pool stays nice and dirty, probably even goes green eventually.
I just scanned this thread, but it was mentioned earlier many times for you to bring the pool to shock level, maintain shock level with hourly testing, add bleach after each test to keep it at shock level and thus... shock your pool. Shock level is in pool school's CYA/Chlorine chart as well as the pool calculator. Enter your CYA level, then put ALL the bleach required to get you up to shock level into the pool.
What's that, 21ppm for 75ppm CYA from the pool calculator? You really do have to add enough bleach to reach 21ppm, at least. You're chasing your tail with anything less than 21ppm and wasting your money on chlorine.
Additionally, turn off the SWG while shocking. When your pool is clear and clean, then you can start it back up. Right now you're wasting the cell life. Plus you need to know the chlorine losses while shocking and if the SWG is on you'll never know.