@Deadalus
I haven't noticed your foam thing using a 1700 litre per hour pond pump to a CIP spray ball in my kegs and for the fermentasaurus, I have the keg upside down so spray going up towards base of keg. I use clear kegs and haven't seen the foam. Sometimes get a bit of an airlock but I just use a separate smaller tube inserted thru the neck to break the airlock.
I am using the Sodium Percarb, Sodium Metasilicate and EDTA purchased from chemical supply company so might not have an additive / contaminant that the " washing products " might have.