How old is the ro?
the reading is taken it hits ro,
ro 2 years old, but this one was used part time, I have three of them now, but only use one.
Will order some pre filters and try that, I may change back to 10 inch if this happens again as I used to change them monthly at £3.50 a pop and 20 inch seem to be way over priced from everywhere, more so if it is the pre filters I will be selling the casings and go back to what would perfectly fine before.......