Your TDS of the fresh water should be as low as possible. My tap water reads 100-200 ppm and reverse-osmosis water should read close to zero, 5-10 ppm.

Just fwiw, I started doing a lot better when I stopped reading meters and starting reading the leaves of the plant instead. The leaves will tell you what the plant needs in regard to nutrients. For example, you said NPK is what you use up, well if your leaves start to yellow, obviously you need Nitrogen. Plants will also curl their leaves in response to ph fluctuations. The plant will tell you the same thing that the meters will, but the plant doesn't go out of calibration or malfunction like the meter.

I think I would like to know if the solution is low in nutrient so I can deal with it before the signs of deficient show and cause stress to my plants.

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A lot of people think that reverse-osmosis water comes from the unit under the sink and I think they are partly correct. For reverse-osmosis to work it requires from 225 to 375 psi for house hold water of which most home do not have better then 60 to 90 here in Calgary. I have a cross connection control ticket and when inspecting the reverse-osmosis system at a renal kidney dialysis centre the pressure is from 900 to 1400 PSI using a booster pump.

I think you mean pounds per square foot. Those psi numbers you are quoting would make stuff explode. The highest-pressure pump I've ever used was a well pump that produced about 50 psi.

My tap water is 30-60 psi, and that is plenty to run an RO filter. I have done it a lot. The filter wastes about 8 gallons for every gallon of RO water it makes.

It is not true R-O with out the psi to force the water through the membranes. The R-Os for houses do not qualify as R-O in my books. 55 to 80 BAR is needed it is about 1,200 PSI. not good in a home with out a very good quality PRV/pressure reducing valve.A normal house has about 11,520 PSF pounds per square foot, or 80 PSI.

I am a plumber with 35 years of experience and have installed many booster pumps in high rises to get water to the top. Most or maybe all of the pumps you have seen are impeller pumps not for high pressure not like the volute centrifugal. Each floor in a high rise need 5 pounds of pressure to get it 10 feet, .434 psi /ft, and 28 inches of water column is 1 pound.

small RO system

I guess that's why my home RO system water reads 10-20 ppm on my tds meter. The system you showed must produce completely pure water.

Also,
Is it possible the higher pressures are required because much larger volumes of water are required (vs a residential situation)?

The high pressure is to force the water through an very very small hole in the membrane. You will notice that most home RO systems say 89 to 99 % removed. The system I showed is 100 %. it is also deionized and made ready for dialysis machines. This is water with no taste at all.

I forgot to mention that a TDS is defined as any particle that will pass through a 2 micron filter.

i am a noob to hydroponics and honestly it never even occurred to me to use my RO water. (!) i've had success with my plain old tap water. My question to you guy.. should i just keep doing what I' doing..if if aint broke don't fix it? or am i going to see great results if i change it up?

You probably shouldn't waste the water if straight taps is doing the trick.

RO came up as a discussion about total dissolved solids.
I would aerate your tap water to remove the chlorine.
Well water can be a problem depending on the location.

Thanks grizzman and Cliver--that's what I wanted to hear ...I tried using well water last year because of the drought---what a disaster, killed anything it touched, hydroponics or not. I'll just stick with tap water.