I recall a video ( which i will give to you if you want, im not at the lab) where bob beck said 100 to 150 microamps ( now there is people arguing on how and where he measured it ) like i stated first of all do no harm. If he wanted to make it stronger he would have. On most of the blood purifiers i have seen they have a resistor in line with the potentiometer to bring the current down, so you could just bypass it. I havent used or tested the sota yet how ever the videos and testimonies was very good, specially the magnetic pulsar