Thanks everyone for the wonderful insights
And sorry for the late reply; I was away from my laptop since morning.
Well I did a 50% water change today and the nitrate seems to have come down below 20ppm. Corals are a bit torn up right now. Almost everyone is closed (other than the freaking mushrooms!). Acros, oh well, are leaching mucus like they always do whenever disturbed. Fishes are doing well, as if nothing have changed. I don't know how but my cleaner and snails didn't get affected by the high nitrate. I just hope the corals open up soon. It has been like 4 hours and they still look beaten up.
Added a new pouch of chemi pure elite in the HOB. Also added natural denitrifier.
Was thinking of preparing another 5gallon water change for tomorrow. Should I do it or wait for a day or two?