what is the maximum level of no3/po4 that is allowed to decrease per day ?

[nghesi]

I have a 64l tank and have not taken care of it for 1 year with 2 clownfish and no corals surviving and I want to revive it. when I measured no3 it was 73 po4 was 0.37. I injected a high dose of nopox 5ml every day and after 6 days no3 is 18 and po4 is 0.03 (hanan test). which means no3 decreases by 10 ppm per day.I want to ask what is the maximum level of no3/po4 that is allowed to decrease per day so that the corals do not go into shock? Thanks

 

[musaabi]

that fast of a drop would have shocked them