Big Dave's Mustard Algae Experiment contribution:
I took the cover off March 26 and topped up.
After adding water, the FC was 10.5, CC 0.0, CYA < 30, and pH 7.4; temp. 64 F. No sign of mustard algae.
Over the next three weeks, I chlorinated with a total of 5lbs of dichlor keeping the FC at 15-20.
The pool collected quite a bit of debris during this period that I vacuumed into the filter; Backwashed on June 15.
June 16, FC 8.0, CC 0.0, CYA 70, pH 7.4, TA 80, CH 11, borates 30; temp. 78 F. No sign of mustard algae.
June 17, FC 7.0, CC 0.0, pH 7.4; temp. 83 F. No sign of mustard algae. We took our first swim - Yay!
June 18, FC 5.0, CC 0.0, pH 7.4; temp. 88 F. No sign of mustard algae, Kids swim. Added Bleach.

I'm not sure If I'll be a good case - time will tell. I've disposed of our old solar blanket that I suspect was harborage for the algae.
With the K-1106, I measure > 1000 ppb phosphate in my pool and 500 ppb phosphate in my fill water.
I have 2 quarts of Kem-Tek phosphate remover on hand and plan to bring the phosphate to 100 ppb.
I also plan to buy a new solar cover in July - We'll see if that brings the yellow back.