The acid job breaks down the scale or opens up the limestone zone , then bailing out the left over sand or other debris in the hole . By running a bailing tool into the hole many times till it's clear. The acid should be spent after doing its work in zone, if it's not spent it will need to be neutralized , or it will come out of the hole hot which is done. There's more to it the that but I think that's what they meant .