I no longer own an Audio Desk, but when I did I used far less than the full bottle of fluid for each tankful of distilled water. Not to save money, but some people were complaining about foaming as I recall and I figured less is better if it still does the job (reduce surface tension to enhance cavitation effect).
Records that had been cleaned in the Audio Desk showed water clinging to the surface in way that was different than other records, which suggested to me that some residue of the surfactant from the AD remained. I couldn't hear a sonic signature from the AD fluid, particularly at reduced amounts, but the idea of leaving some chemical on the record did cause me to change my process. On the other hand, I know plenty of people who are very happy with their ADs and I have played records that came from them without a problem. I currently do a rinse cycle using different equipment, but part of that is due to how I prefer to dry the records after an ultrasonic cleaning.
Records that had been cleaned in the Audio Desk showed water clinging to the surface in way that was different than other records, which suggested to me that some residue of the surfactant from the AD remained. I couldn't hear a sonic signature from the AD fluid, particularly at reduced amounts, but the idea of leaving some chemical on the record did cause me to change my process. On the other hand, I know plenty of people who are very happy with their ADs and I have played records that came from them without a problem. I currently do a rinse cycle using different equipment, but part of that is due to how I prefer to dry the records after an ultrasonic cleaning.
