I've heard about the Potassium Monpersulfate...it's not going to help you. Neither is ammonia based algaecide.

You are OK using the Cal-hypo but only OK. As you were told, without diluting the CYA down to a manageable level you won't get your pool clear unless you reach and hold an FC level of 25ppm and thereafter have to maintain it between 8 and 15. Until you get your FC to the appropriate shock level for the amount of CYA, you are fighting a losing battle.

The Cal-Hypo may make your water cloudy but it will be a milky cloudy as opposed to a green cloudy--and it's better than algae.

But do not despair! The fix is not complicated, just takes patience and persistence. You can read up on the same advice we are giving you in the Algae section here at PF. It actually works and it's not magic or mystical.

It's simple. You have to kill the algae and keep making sure it and its capability of starting up again is dead. You do that with lots of chlorine maintained at a continuous high level so the algae cannot "regroup". There is no magic cure, magic bullet or "special" trick. Just lots of chlorine.