Rushton's DIY approach to ultrasonic record cleaning published by Positive Feedback

A friend pointed out this thread to me today.  Thanks for all of your contributions.  I will be making some adjustments to my cleaning solution mix.
I've been using a DIY ultrasonic cleaner for about two years now.  I use an 80 kHz Vibrato tank and turn three records through the bath at a 5 minute per rotation rate.  My record spacing is about 1 inch.  
Rushton's recommendation of a maximum bath temperature of 36 degrees Celsius accords exactly with my experience.  At higher temperatures (40 degrees plus), and while using a 60 kHz transducer, I did rarely experience some permanent vinyl deformation.
i agree also that regular tank filtration (1 micron filter) and periodic cleaning fluid replacement are essential to success.
in comparing the results of the 60 and 80 kHZ transducers, I found that the 80 hHz machine was the superior cleaner but that it required longer bath times.  The Vibrato machine I use has both a thermostatic control and a timer shut off.  Consequently, I don't hesitate to leave particularly dirty records (I buy many used ones) cycling for 35 or 40 minutes at a time.  
Given prolonged exposure, the finer cavitation bubbles of 80 kHz machine ultimately remove the dirt more effectively than the 60 kHz.  The finer cavitation bubbles and limited bath temperature allow extended safe exposure of the vinyl to the bath.  

Yes, I've used the Vibrato machines in my record cleaning systems.  I found Louis, at Vibrato, to be a very reliable guy.  
I was influenced initially by the work of a Texan who published his methods and materials on a different forum a few years ago.  He got me thinking about particle sizes and ultrasonic frequencies.  
I began with a 60 kHz Vibrato machine, which worked very well.  A number of factors led me to believe that longer, gentler cleaning was a more effective and safer approach.  So, I bought the 80 kHz machine.  While the cavitation bubbles of the 80 kHz machine are most effective at removing smaller particles, I found that if I ran the record for a longer time those smaller bubbles did remove larger particles as well as the 60 kHz system did.  Also, I experimented with timing motor speeds and the cleaning solution mix.  
My testing has been by ear.  I listen to a record and clean it until I am satisfied that it has stopped improving.  This listening test led me to conclude that the 80kHz machine would clean more effectively than the 60 kHz machine.
One downside of my approach is that record cleaning takes more time.  Since I enjoy the process that is not a burden for me.  
I use cork stoppers large enough to cover the record label between the records as I mount them on the spindle.  These cork rings are 1.25 inches thick.  I mount three LPs at a time, which leaves them approximately uniformly distributed between the tank walls in the bath.  I did not perceive improved listening results when I have increased the distance between LPs (2 LPs per cycle).  When I tried more than 3 LPs per cycle I did begin to see some impairment of the water circulation movement.  So, I've stayed with 3 LPs.

Rushton,
We hobbyists can be drawn too far down a path sometimes.  Since LP enjoyment is so dependent on the LP surface condition, I felt the extra step was warranted in this case.  Also, I built a couple of extra machines and sold them to other audiophiles in order to fund my experiment.  My largest investment in ultrasonic cleaning has been my own labor to develop, build and operate the machine.  It has been a pleasing way to spend my time.
One thought to keep in mind.  If Louis uses a new tank with a drain, that may alter the outer dimensions of his machine.  That might have some impact on the cleaning system into which you are placing the new machine - just something to check before purchasing.