I'm getting ready to put a coat of DryLok on my basement cinderblock walls. There was quite a lot of efflorescence, which I removed using a muriatic acid dilution.

The powdery efflorescence came off fine, and most of the crystallized stuff, but there are still some areas with very hard material. It's difficult to tell what it is -- efflorescence or just rough cinderblock, but I think the former. Repeated scrubbing seems to have done all the good it can.

So my question is, have I done enough to go ahead and apply the DryLok? How important is it to remove every last trace of efflorescence? And if it is important, what should I do to remove this stubborn hard residue?

Thanks.