Spray the inside down. Mix up some dilute chlorine ( a cup or two per 5 gallon bucket) and slosh that around inside. Then fill it back up.
Add 30 ppm CYA at start and once you have that dissolving raise your FC to 12 ppm. Do a quick SLAM to get any thing left behind.
This question may be too general to answer but I'm curious. This is my 4th pool, put up last summer. Each has lasted an average of 7 years. They have all been maintained using pucks in ducks, powdered pH up/down, test strips, and the cheap test kit. I can only remember one other time when the algae got so bad that we had to drain and refill. My now deceased boyfriend used to take care of blooms with algaecide, powdered shock, and floc. Why did that work? Were we just lucky?
It will work. I just would not want to swim in the chemical stew that results. The water was never as clear as TFP clear. The pool most likely was not sanitary as the FC/CYA levels were not maintained.
Eye irritation, itchy skin, feeling like you need to take a shower after getting out of the pool, etc. TFP pools are not that way.