Membranes passing .02 normal ?

[bees1st]

My RO is in its second year . Last year it passed no sugar, this year it's passing.02 . I was told by the rep that this is normal. Just wondering what others have found . Am I being fed a line or is this indeed normal ?

[DrTimPerkins]

My RO is in its second year . Last year it passed no sugar, this year it's passing.02 . I was told by the rep that this is normal. Just wondering what others have found . Am I being fed a line or is this indeed normal ?

It depends upon the membrane. Typically it is a matter of processing rate versus sugar retention. Very fast membranes generally pass some sugar. Very tight membranes have lower throughput.

At 0.02 I'd wonder if your refractometer is correct. They get a little squirrely at such low concentrations. I'd suggest collecting a bit of permeate, calibrating your refractometer, then reduce (boil down) a quart of permeate to a half-pint and measure the sugar content again (after it cools) and multiply that reading by 4. That'll give you a much better reading of the actual sugar content in the permeate.

[wiam]

It depends upon the membrane. Typically it is a matter of processing rate versus sugar retention. Very fast membranes generally pass some sugar. Very tight membranes have lower throughput.

At 0.02 I'd wonder if your refractometer is correct. They get a little squirrely at such low concentrations. I'd suggest collecting a bit of permeate, calibrating your refractometer, then reduce (boil down) a quart of permeate to a half-pint and measure the sugar content again (after it cools) and multiply that reading by 4. That'll give you a much better reading of the actual sugar content in the permeate.

Multiply?...

[bees1st]

It depends upon the membrane. Typically it is a matter of processing rate versus sugar retention. Very fast membranes generally pass some sugar. Very tight membranes have lower throughput.

At 0.02 I'd wonder if your refractometer is correct. They get a little squirrely at such low concentrations. I'd suggest collecting a bit of permeate, calibrating your refractometer, then reduce (boil down) a quart of permeate to a half-pint and measure the sugar content again (after it cools) and multiply that reading by 4. That'll give you a much better reading of the actual sugar content in the permeate.
I've been testing with a hydrometer, and I did check the accuracy of zero on this with water it's good

[Bricklayer]

Are you using a digital refractometer?
I've got a Hanna digital refractometer and I usually use it for testing my syrup. But sometimes I do use it for testing sap. What I do now after getting some pretty squirrelly readings is
After any sample I wipe it out with a eyeglass cleaning fine cloth and put a couple drops of permeate or distilled water in the eye cup and swish it around. Dump it out then wipe it again.
If you tested your concentrate first then there might of been a little droplet of it left in the eye and when you put the permeate in it mixes with it.
And if it has temperature compensation then once you put your test sample in the eye let it sit there for 20 seconds and let the temperature comp do its thing. Usually the numbers are on the bottom corner. Once they stop fluctuating it's good to go. Press test.

Works for me.

[SSFLLC]

heck your oil rings on the inside of your covers. Where the nipple part of the membrane goes. Had one with a crack in it that passed the same amount of sugar on first pass and much more on second. I have the same RO.