Whart - Yes, your cautionary message is correct. You do need to be careful of the alcohol. I only use a small amount in the mixture. About 1/2 a cup in close to 1-1/2 gallons of distilled water in a vented area.
Some people don’t want the alcohol at all and that’s fine too. If not rinsed off the alcohol can dry out the vinyl but it does help clean well. So find a method that you are happy with. The cleaning mixtures that companies sell are usually expensive and are probably 90-99% water depending on the company. Find what works for you and the best that you can afford.
I use mine a couple times a month. I usually buy 3-4 used records each month and also re-clean a couple or so that need it while I have the water and unit set up. I do about 8-10 records per tub of water mixture. Then just dump the water, dry the machine and store it in the garage. I almost built up a water filter system for about $100 or so which would clean the water down to .5 microns and used a little 12V pump but soon realized it just wasn’t worth it. 6-10 records is as much as I ever do and the small amount of water is cheap so what’s the point. If you run it more then I can see filtering it.
I think even a cheap ultrasonic cleaning system is much better then the old vacuum type systems. Although it would be great to have a vacuum unit to suck the water and any residue off the record after the process!