To be exact, I added 1.2gal at 4pm, tested at 8pm (.4FC/4.0CC). I added 1.75gal right after that test. Today I tested at 1pm (2.0FC/7.6CC). Added 2.4gal at 2pm. I'm off to buy more chlorine now and will test again when I get home, which should be about 3hrs since adding. I have the pump running at full speed but I do slow it to about 2600rpm overnight because it's pretty loud.
Also, from the FC drops you are seeing it appears like the Algae got a pretty strong hold. You’ll want to seek out any hiding places where it can lie in wait for the next attack. Tube rails on the ladder, in and all up in the skimmer/weir door, water features, etc. anywhere that bad water can hide or algae can attach itself.
Just got done with a good scrubbing. I tested and added more chlorine. The water is looking great and CC is below 0.5 but my FC is still very low (almost zero). Strangely the CYA is down to 15 and pH has dropped as well. I had expected pH to rise at least while slamming.
I’m tempted to add some tricolor tablets again to help boost FC and CYA. Is this a bad idea? I’ve ran the tests many times and even used this Lamotte ColorQ device. Both manual and the machine match pretty closely on CYA and FC. PH shows 7.6 on the machine while eyeballing with Taylor looks closer to 7.2 or 7.4.
I’ve turned the jets upward to aerate for now. I think I’m near the end of the slam as long as I can get the FC up.