Premium distilled water for ultrasonic record cleaner

IMO, using expensive double-distilled, RO purified, or reagent grade water is probably overkill.  Even distilled water from the grocery store only has a few ppm of impurities, something overwhelmingly contaminated from the junk on your records.  It might be interesting for someone to do a water conductivity study over the course of cleaning records.  I think the best course is to change the water regularly; I change mine about every 25 records. I also wipe off the superficial dust and fibers with a microfiber cloth before cleaning.  If you want to use the expensive ultra-pure water, by all means do so but I would wager its conductivity to increase significantly after only a few cleanings and therefore higher than that of new distilled water. 

Rlawry

a very large % of my records are new or mint / mint -

perhaps an identical ultrasonic machine with cheap distilled water (like I was using) for old records

great point, sorry I couldn't resist having fun

Only ever use premium quality oxygen-free, cryogenically treated, zero ion pure, RoHS compliant 100% H2O variety water.  Only use that water after all the bad electrons and lithium grease has been filtered out.  Don't use cheap imitation water. 

For best results, use water that has been removed from vacuum mines after vacuum mine implosion accidents.  Many think that idea sucks, but performance is much better than artificial H2O.  Compliments will rain down.  Using artificial water will result in low performance as will artificial vacuum. 

Don't use water on mint records because everybody knows that mints melt in water.

To Rlawry's point: I pre-clean virtually every record that goes into the ultrasonic, to reduce the amount of contaminants that pollute the bath. There's no 'one way', but using a conventional vacuum record cleaning machine with appropriate fluids, followed by a pure water rinse, is a predicate to the next step of cleaning in the ultrasonic. I buy a lot of old records, and even with pre-cleaning, change the ultrasonic water out at roughly 50 cleanings.