Dunno what your pressure was with CLEAN, NEW cartridges, so I can't say.

But, what I can tell you is that cleaning with muriatic acid is NEVER the first thing to clean with, and usually isn't needed at all. It won't remove grease and people goo . . . and reportedly (I've never confirmed this) can 'set' the grease so that you cannot remove it.

Probably your filter has some "how to clean" instructions that you'd be better off following.