nutrient export would be skimmer, gfo, algae scrubber, macros ect..
Are you using RO water for the water? How much do you feed the tank? Anything else die recently?
I would be doing 25g everyday or every other day at least until the number came back down into exceptable ranges. But need to figure exactly what is causing the spike in the first place or the problem wont go away, so some more info on your tank would be helpful. Like livestock in the tank, your daily and weekly routines for maintenance and feeding would also be helpful.