What is you PO4 out of interest?
Just wondering what fish you have & how much you feed the tank in comparison to the rated size of the scrubber?
I would use the filter socks, & clean them once a week.
I would also give the substrate a good clean.
I would run GAC.
There's something not right for the tank to get to the state its in.
You need to solve the problem or it may come back after its corrected.
Phosphate measured on Red Sea kit