Hey doll! I have not tried the ultrasonic cleaner. I have actually heard mixed
reviews on them...some swear by them and others say it's a waste of time. I soak mine in VERY hot water then I will flush them with a baster....I take the bulb off, drop the carto in, replace the bulb and run water in and out of it....again very hot water. Seems to work just fine
I have used a syringe in the same manner, but you don't get nearly as much water into the syringe.