Efflorescence

It’s just minerals seeping out, can’t really stop that. Just sell them on a monthly treatment, I do that for rust control.
I’d go there once a month

So then what can I do in the meantime? This is a residential customer so it’s their home. Is there nothing I can do for it to at least look better?

What do I tell the customer at this point?

Did you explain to the customer what efflorescence is?
It should be in your contract stating that hey we can remove the top layer on the wall, but it will be coming back. We dont guarantee that it wont come back.
This is why so many of us dont do efflorescence jobs, because you remove it then it comes back and the customer want you to come back out again for free.