Best ultrasonic lp cleaner in 2020 and what surfactant best?

Don't necessarily take me literally about 2 drops but a small amount on that order of magnitude is what I personally use.  Others may do differently and they are not necessarily "wrong".  I use a higher concentration of isopropyl alcohol, maybe 20%; I have forgotten. 2% of alcohol would do almost nothing, IMO.  It would evaporate away rapidly, first of all.

ml89009, Triton X-100, recommended by Mijostyn, is a non-ionic detergent, otherwise known as "2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol".  It is a true surfactant used mostly in biology and I suppose for industrial processes.  Kodak Photo-flo is a mixture of propylene glycol (20-40%), aka "anti-freeze", and a non-ionic detergent that is probably in the same family with Triton X-100 but is chemically a bit different.  The non-ionic detergent component is less than 10% of the make-up of Photo-flo.  (I just looked this stuff up; I don't pretend I always knew it, but I have known not to use Photo-flo, though many do.)  Propylene glycol is arguably not good for LPs.  I always use Triton X-100 which comes in near 100% solution, and little bit, a drop or two in a liter of cleaner, is all you need.  There are other pure non-ionic detergents, e.g., Tween-80, Nonidet P40, etc, that are either identical chemically to Triton X100 or work just as well. These compounds make the water "wetter"; they lower the surface tension so the cleaner can get into tiny more hydrophobic spaces on the LP. Mijostyn is right.  I'm a biologist, used these chemicals throughout my career in molecular biology.