Your title has it right. It’s just about dialing it in for your specific pool with its parameters. Meaning, latitude, sun/shade, usage, etc. You said you are shooting for an FC of 3. What is your CYA level? And preferably, if you can supply a full set of test results just to make sure our guidance for you is accurate. You are not currently sharing your Pool Math logs. If you subscribe to Pool Math, you can save test results. Then you can share them and we can see them. My signature has a link to my logs as an example. What test kit are you using? Hopefully one with a FAS-DPD drop method for testing FC. It’s really needed for accuracy.
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I need to frequently fiddle with my SWG output % since I have an autocover and it is on for varying amounts of times in the spring, which greatly changes the need for FC from day to day. For example, by CYA is now 80, but I let my FC get up to 15 because I had ramped up pump run time for when it was open last weekend, but didn’t lower it when it was cool and covered this week. No worries, I set it to 0 for a few days. It is currently dropping.
SWG’s aren’t set and forget, so you will always be checking your FC every few days to see how its tracking.