How to pre clean a very dirty LP before Ultrasound Machine?

I use a SpinClean with distilled water and the proprietary detergent before the Ultrasonic.
+1 slaw. Taking a steam cleaner to them sounds faster. Especially if the were on dish drying racks. I'd only use distilled water in the steam cleaner.

why are you worried, that’s what a sonic cleaner is for. spin clean is not saving you anything, you’re going to use the same amount of distilled water cleaner and more time. I’ve putt some very dirty industrial parts in sonic cleaners, crusted with gunk ,baked on usually and they clean them nicely. Yes you need to change the water more often but you can also rinse after if needed to save time and D-water. You can let the cleaning water get surprisingly dirty if your rinsing after FYI. that rinse could be in a Spin clean too if you have one. no detergent in the rinse of course. oh one more thing particles tend to drop out of suspension in a sonic cleaner. (unless they are buoyant of course) 

Sorry, it's called GEM Dandy record cleaner made by Merrill.