VPI Record Cleaning - Does Bidirectional cleaning really make a difference?

I would assume that some dirt particles are abrasive.
I only tried Audio Intelligent three step so can't compare to other fluids.
I also had a few records cleaned by Audio Desk ultrasonic with pre-cleaner and water on VPI 17 before that and double rinsed with water and vacuumed after. I did compare the same albums the same pressing with the records cleaned by me on Okki Nokki with Audio Intelligent, double cleaned and double rinsed with water each time.
I heard no difference, both were very clean. However, I don't have a high resolution rig so perhaps there is a slight difference. Still, my system is very sensitive to small changes of whatever, so resolution is not bad at all.

inna,

I have a MoFi brush and two Disc Doctor brushes and they are essentially identical. As for your concern about scrubbing the record with these brushes causing damage is concerned, you seem to be thinking that the bristles of the brush actually can get down into the grooves, or that the dirt is abrasive. Neither of these is really likely, but I will take it under advisement. I have owned my HW-17 since new, purchased in 1990, and have used it on literally thousands of records. None have been hurt as far as I can tell. I think we can agree that the reverse motor feature is nice to have, however, I stand by my original post that it is not essential. As far as cleaning fluid goes here is a recipe that works quite well: 1 gallon of distilled water (pour out 1 pint), 1 pint of isopropyl alcohol (99% if you can get it), 2 drops of liquid dish detergent, mix well.

Taters,
You are probably right.

Inna,

I thought the mo-fi brushes were a copy of the Disc Doctor brushes?

I've had a VPI 16.5 for years. I turn it on and scrub the bejeezus out of the record as it rotates. If necessary, I rinse (vacuum) and repeat. I use my own home remedy for a cleaning fluid. My friends use it too. Its as good as, or MUCH better than anything sold commercially out there. And it costs pennies per gallon of distilled water for the active ingredient. It really gets the gunk out of the bottom of the grooves, doesn't harm the records and really improves the sound. I've cleaned thousands of records this way, and harmed none of them. 

Wrong. This is no substitute for bidirectional motor. And unless the record is very dirty you don't want to scrub it, if you do you push the dirt deeper into the grooves. You move the brush rather gently while applying fluid, agitate a little. And Disc Doctor brush is better than Mo-Fi.

I have an HW-17 and definitely think the reverse feature helps.  But, it is not essential if you wet the record and then turn off the motor and use a MoFi brush to go back and forth over the record surface much as you would do to wash a dinner plate.  Then turn the platter back on to vacuum it.  This works because you are scrubbing the record in both directions anyway. 

Okki Nokki is $500 from the distributor and it does both direction. Has pretty good vacuum too. I use it with Audio Intelligent three step cleaning system with excellent results. I read here that bidirectional does make a difference.
I did not compare it to VPI.