You need a current limiter for sure and a DVMM to measure current and voltage.
You need the voltage across your cell to be 10V (probably more though I can't tell you how much more) given your electrode spacing is much farther apart than the normal 1.5" (3.8cm) we use.
You need to know current so you can use Faraday's law of electrolysis to calculate the run time so you know what you made and Faraday's law ONLY works if you have a constant current flowing through the cell (current limiter).
You need to produce slowly enough that the silver oxide you're pulling into solution (what that greyish stuff on the anode is) actually dissolves. Run too high a current and you make LOTS and LOTS of silver oxide (ionic silver) that starts to precipitate out and it will NEVER reduce because its not IN solution.
The solubility limit for silver oxide in water at room temp (75F) is about 22PPM. At 150F its about 40PPM. If you EVER get to a concentration greater than the solubility limit at the temperature you're running, absolutely you're producing silver oxide that will never reduce and thats not good.
There is NO "meter" that measures the PPM of colloidal silver. That use a TDS meter wives tale is just that. Its BS. It won't measure colloidal silver content. The ONLY way you know PPM is to have a current limiter and run the Faraday's law equation given the desired PPM and quantity of distilled water you're using in the cell and the current you're running through the cell to compute the time to run the cell. When that time is reached you have the PPM you wanted.
As far as how much current? With an anode that size, 10-20 MILLIAMPS! Thats 0.01 - 0.02 amps.
Unless you're making 20PPM, you'd want to add the correct amount of reducer, plus a little extra for "insurance" and to speed up reduction a bit at the BEGINNING of the run. With the need to keep the PPM below 20-40PPM depending on the temp you're running at, you need to reduce the ionic silver you're pulling into solution as quickly as you can so you can get the PPM up over that as colloidal silver. If not, the ionic silver above this level precipitates out of solution and will never reduce and now you're drinking a soup of ionic silver and colloidal silver and thats not good.
Those little whiskers we jokingly call "smoke". Thats a dead indicator you're running way too high a current. Thats silver oxide that is NOT dissolving. Just because you're stirring and don't see it doesn't mean anything because the stirring simply distributes the silver oxide particles evenly so you can't see them (they're individually microscopic with no perceptible color) but they're there.
But then you have no clue how much current you're using and without knowing the voltage across the cell you don't know what you're making because there are requirements for cell voltage to be 10V minimum with a 1.5inch electrode spacing (higher with wider spacings) - its VERY important for proper manufacture of colloidal silver (silver oxide - the electrolysis phase).
You need to make a current limiter and run at the very low current I mentioned. With stirring, if the surface area of your anode is about that of a 1oz silver bullion bar, with stirring, maybe 20-25milliamps (0.02-0.025 amps) MAXIMUM!
Looks can be quite deceiving. Given you can't measure what you're making where the only way is with Faraday's law, who knows if the color is due to the silver oxide that actually DID dissolve in the water and got reduced where there's still a lot of undissolved microscopic particles that will remain silver oxide forever?
Ingesting silver oxide causes a condition called argyria. The silver oxide is converted to silver chloride in the stomach which is still an ion. It gets into the blood, into the cells of your body because it is an ion (colloidal silver isn't - it can't get in), reacts with sulfur and/or selenium inside your cells and is converted to silver sulfide and/or silver selenide which are now NOT ions so they can't get back out and are stuck inside the cells forever. Silver chloride, silver selenide and silver sulfide are ALL light sensitive. Silver chloride is the salt they use to light sensitize phototgraphic film. So... get enough inside the cells, get enough light exposure and you smurf yourself (seriously) AND its PERMANENT. OK, if you stop, given the body basically replaces itself once every 7 years, the blue will eventually go away but it'd be measured in years, not minutes, hours, days...
Ionic silver has little to no disease fighting ability. Colloidal silver made from it is 25-30 times more potent weight/weight.
Also, another aspect with producing too quickly is that what does reduce creates particles of colloidal silver that are large compared to the range we want (10-15nm). Larger than 15nm starts getting into the "brownish/reddish" color range where those particles are too big to be absorbed and hence, they're just going in one end of the "people" (wink) and coming out the other end with nothing good happening in between (wink).
As far as a current limiter, 2-20ma is a good range. More than likely you'll be operating below 20ma or at. Voltage doesn't hurt. A higher voltage across the cell is better. 10V at 1.5" electrode spacing is kind of a minimum. Its below this that you run into issues.
The power supply for the current limiter needs to be maybe 5+V higher than the maximum voltage you observe across your cell when running so it remains operating properly. It needs some voltage to operate too plus a little safe area above this (wiggle room) where the maximum voltage you can put across the cell is the power supply voltage minus this "headroom". For lower current, a laptop charger (19.3v) works just fine. Its what I've been using for years. I don't stir though. I've read that stirring increases the path the electrons have to take from anode to cathode and will actually increase the voltage of the cell to where you may not be able to get it down to 10V. As I said this is fine and actually desirable but not if that voltage causes your limiter to stop functioning properly for being higher than the maximum, given your power supply voltage and limiter headroom, you can put across the cell and keep everything functioning properly.
I'm sure others will chime in too.
Build an LM317 limiter as has been discussed on here, even recently. Its all of 3 parts - the LM317LZ, a fixed resistor and a potentiometer. Thats it! It can't be any simpler. It works, its cheap to build (LM317LZ's aren't expensive, nor fixed resistors no potentiometers) and plenty good enough for making Colloidal Silver.