A TDS meter is testing for dissolved solids in the sample, a PH meter just tests the PH, or acidity/alkalinity.
A TDS meter is testing for dissolved solids in the sample, a PH meter just tests the PH, or acidity/alkalinity.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.
Thanks Maple Flats.
With a tds meter I would want the reading to be 0 ppm? And with a ph meter I would want the reading to be 7, which is neutral?
You will likely seldom if ever attain either of those readings. Dr Tim might have an answer but my guess is that permeate, while it should have zero sugar, it will not generally have a PH of 7.0 nor will it have no TDS. I don't know for sure but I doubt there are no TDS in permeate, and while the PH might be slightly off the 7.0 mark. An RO removes water from the sap because the sugar molecule is too big to pass thru the membrane, other disolved solids might be small enough to pass. Also, passing thru the membrane won't likely neutralize the water, but if it removes some of the causes of the PH it could bring it closer to neutral.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.
Generally you want your sugar to read as low as possible, but some membranes sacrifice a small amount of sugar passage for higher processing rates. Depends upon your membrane/strategy. Note that refractometers often don't read accurately down that low, so even if you see 0.1, 0.2, 0.5 Brix, it might still be zero and either your refractometer isn't calibrated or just not sensitive enough.
pH of permeate is typically a bit acidic, 5.5-6 is not uncommon, but it'll depend on the starting sap chemistry and your processing (membrane properties, etc.).
For dissolved solids, typically you want it to be very low, under about 50 μS/cm. Again, some membranes trade-off leakiness for speed.
For those uber geeks among you, https://file.scirp.org/Html/4-3002254_89798.htm
Dr. Tim Perkins
UVM Proctor Maple Research Ctr
http://www.uvm.edu/~pmrc
https://mapleresearch.org
Timothy.Perkins@uvm.edu
Thank you both for your input. 2021 will be my first year at using a homemade RO.
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