Slop Oil Chemical Treatment-residence time

[airbus]

I get a bit upset when I ask a chemical reps about what would be their chemical ttreatment recommendation on for a new slop oil treatment system. The answer I get covers the basics such as this many pumps, heat source (sometimes), mixing source (hardly ever mentioned), type of chemical/dosage (upon slop oil analysis) but never how much residence time would be required for the chemical to be effective (this will let you to evaluate if the slop tank is of sufficient capacity to allow for treatment). Are there any "operating/design practices" that would address this issue?