checking for sugar passing with a meter

[Jeremy Steeves]

I heard you can use a tds (total dissolved solids meter) to check for passing sugar in the permeate, what kind of readings should you look for, like a sap reading and a permeate reading, then compare that with retention (I have xle 440's with 99%)?
I want to know accurately that my RO is really not losing sugar, better than a sap hydrometer.
Any insight appreciated, thanks.

[Amber Gold]

Conductivity meter is what you're looking for.

The alternative, which is also accurate, is to take say a gallon of permeate, and boil it down to about a cup. If there's sugar being passed, the sap refractometer will easily pick it up.

[brookledge]

Just do what josh said. It takes a few minutes to boil down some permeate. I have done it and started with a quart and boil it down to test with a refractometer. If you are going to use a hydrometer you may want to start with more permeate so you have enough to fill the hydrometer cup
Keith

[OldManMaple]

My RO came with a TDS meter mounted on the panel. I use it when flushing the membranes. Sorry I can't remember numbers but I think concentrate was in the 600 ppm range and I would run it down to about 30 ppm on the flush. It seemed that it took along time to bring it to zero and wasn't worth it. I have a hand held meter that came with my house RO. I use that for my permeate and that you want to be Zero. Hand held TDS meters are only in the 15.00 to 50.00 range and quicker than boiling down permeate and I find myself checking it more often. Hope this helps

[Justin Turco]

I cut and pasted this from an earlier post that I had here:

Brad at leader had me concentrate some permiate the other day. I set the ro to produce 4 parts permiate and 1 part concentrate. I then tested the concentrate (the concentrated permiate..that is) I came up with something like .20 of 1 percent on my sap hydrometer. I then divided that number by 5. This is the amount of sugar in the permiate. It amounted to about 1 gallon of syrup lost per 2,000 gallons of sap processed. We agreed that I should keep running my membrane. This is a pretty good technique I think because of course...when I just put the hydrometer in unconcentrated permiate, it looks like zero sugar content.

[Diesel Pro]

Taste is my quick check. Then I use my digital refractometer to make sure it's scoring zeros.