spongy crap sounds as if there is a serious gaak prob.
Prior to acidifying after separation from the base solution, do a few warm and cold h2o washes on the NP.
If this doesn't remove the spongy crap from the NP, don't worry too much as it shouldn't migrate into the h2o layer if titrating.
I don't know if Ibee'd gas the NP with it being present.
If gassing, maybe it will filter out.