@slaw - a few years ago, I was doing some research for a piece on DIY US (after having owned both the Audio Desk and KL). One of my sources of information was a long time manufacturer of factory line sized ultra sonic cleaning systems. (He didn't focus on vinyl, but was willing to spend an hour and a half over the phone and provide me with a lengthy email). He was emphatic about the value of a surfactant as part of the US process- it improved cavitation effect immensely. He showed me metal parts cleaned with and without surfactant (granted, not vinyl LPs, but still). When I jumped on the KL after the Audio Desk, I thought- simple- no chemicals to rinse off, no kludgey spinning applicator brushes, etc. But, the KL doesn't allow for the use of surfactants (I haven't confirmed that directly with KL but suspect I am right). The DIY US, from my perspective, actually brings more to the table than either commercial, made for vinyl, US cleaner. You can add surfactant, and avoid some of the complications of the Audio Desk design; you can control heat, degas, and build a recirculation system with a filter (something KL now offers, but still no surfactant). And, your price of entry can be cheaper. When my KL finally dies, that's the way I'm going. (I still pre-clean on the Monks, and for certain records, do a reagent water rinse after the KL). For now, I'm changing out the water at 30 records or less, even though with pre-cleaning there is very little residue in the KL tank. (If I put a new record straight into the KL without precleaning, there will often be some grit in the tank when I drain it).
