Yes I understand the process.You are getting low nutrient readings because of the algae growth in the tank. The nutrients are fueling the algae growth.
Rebooting the tank for an algae issue isn't necessary. Ultimately, it comes down to finding and eliminating the source of the nutrients.
If your dry rock was not cured before placing it in the tank, the organics in the rock will cause a huge algae bloom. But if the rock is already placed, you might as well ride it out. Eventually, it will clear up.
I believe the rock it is leaching PO4 which is causing the growth. I have taken all logical step to abate it. it is not clearing
The Rock was bleached for 5 days before use to kill off any organics. Rack was cycle in tank without issue over a year ago