Agilent SB-Phenyl Column Backpressure increases after wash

Hi everyone
I have an Agilent SB Phenyl Column  that I used with a mobile phase with PH 6 and ACN (50/50) every time I use it I wash the column making sure to replace the PH 6 with water but whenever I re-use it with my mobile phase the backpressure increases. is there any suggestion for whats's wrong or a wash solution for this case please ?

Was this helpful?