Welcome to the forum, you're at the right place to learn. I'll see if I can help, from one rookie, to another:
If you haven't already, have a good read on the 'Articles' Forum, as well cfnisbet's excellent threads on Colloidal Silver production:
https://www.cgcsforum.org/index.php?topic=4965.0The multimeter (MM) is connected properly, according to your description.
Does your power supply (PS) have a CC indicator light? If so, is it coming on?
The process is governed by the amperage, not the voltage. I just set my PS to maximum voltage -30VDC is fine, & the amperage to about 4-5mA {the voltage will be what it is}. Power supplies aren't designed to operate accurately at such low amperages, that's why you use a multimeter, connected in series. As long as the CC light remains constantly on, & the VDC doesn't drop below 10VDC, then you will be OK.
I leave my PS display set to maximum voltage (about 24VDC), & ignore the PS amperage rating, as mine is usually out by up to 1-2A. eg. my PS will show a 4mA rating, whereas the MM will indicate 530-570mAs. So it's always best to refer to the MM.
It is recommended to initially switch on the PS, for about 3 seconds, to gauge the mA, adjust if necessary, to attain about 5mA. Quickly retest, then do the calculation {your calculation is good}, & switch on for the Colloidal Silver production run. If you have 0mAs, then something is going on, that shouldn't.
Have you added the electrolyte? I forgot once, & had zero mA, as distilled water has virtually no impurities, it will struggle to generate a current.
Are you sure the MM hasn't blown the mA fuse? Try setting the MM to the 10A, & see you have a reading there. It will work, just be less accurate -show 0.005mA, as opposed to 500mA, when the MM is set to the mA rating.
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See how you go. Seems your basics are sound. If any of the forum's experts note any inconsistencies, then please correct me.