Michaelab, I have to research the tarp method. How does it even work? The weight of the water woudl pull down the tarp in a second unless there are some serious stakes/weights applied to hold it in place. Whatever the case, I did the simultaneous drain/fill and I probably ended up wasting a lot of water that way, but you gotta do what you gotta due.
Long story short, I am hoping that having performed this and getting my levels dialed in, I will be able to squeeze some more time out of the current plaster job to avert having to resurface sooner than later. Former owner said she had drained some last summer, but it must have been very insignificant if the starting CH was 1500, and the CYA was >/= to 110. Guess her pool guy was using the common place method of tabs and what not. I have a feeling she must have done a partial drain, and then fill separately b/c maybe that is what exacerbated the plaster and cause a small bubble then delam for me.