So I went to the pool store and had them test the water. They have a fairly sophisticated setup. They have a bunch of square-sided "testtubes" that each have powdered reagents in them for a set test. They use a pipet to inject water into each one and then use a computer controlled colorimeter to directly measure and record the readings into the computer. Any way, here is what they came up with:

Chlorine Total and Free both 3.8
pH 7.7
Alk 90
CU & FE ~0
Stabilizer 10 ah ha!, BUT wait...

How can we believe the stabilizer is only 10? Wasn't it on Saturday that I added four pounds of CYA to my 20x40 IG pool. Doesn't that increase the level by about 30 all by itself? So, now what????