Good you have a proper test kit. SO when it's cloudy, your biggest responsibility is to ensure that your FC always stays at or slightly above the SLAM/Shock FC based on your CYA. It must never drop during the SLAM or you lose progress. As with any SLAM, you "MAINTAIN" that higher FC level until:
1. Water is clear
2. You do not lose any more than 1ppm of FC overnight (that's the OCLT)
3. CC (Combined Chlorine) is <.5
** You MUST meet ALL 3 items above to properly do a SLAM. Simply “spiking" the FC higher than normal isn't SLAMming, therefore there’s a good chance your algae will return.
During the SLAM, your primary testing will be for FC only. CYA doesn't change quickly and CC you can check towards the end of the SLAM when you think you are getting close. At the same time, continue to run your pump 24/7. Remove any “muck” and debris, scrub all parts of your pool to expose any algae, and vacuum/clean (or backwash) filter as necessary. You may have to do this several times. It's a lot of babysitting, but with patience and consistency, you will succeed. Good luck!
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Here's a very important note: You MUST be sure of your CYA reading. Mix the solution in a bottle, pour into the skinny tube to watch the black dot, and do this test outside with your back to the sun. After your first attempt, pour it back to the mixing bottle, shake, and test again. Do this 3, 4, 5 time if you need to so you have a consistent result. It is absolutely critical you have a good CYA reading to ensure you can have the correct corresponding SLAM/Shock FC level. Of course with a CYA as high as yours, you will need a high FC level, but it can be done.
Can you tell us what test kit you used for those numbers? It helps us guide you.
