What's your TDS threshold?
- Thread starter Mozby
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MolaMola
Supporting Member
Pressure is a hair under 60 psi.
No, I do not flush membrane every time. Should I? By removing flow restrictor and letting water pass through?
I would say we normally make 25-50 gal at a time. Maybe less on occasion. Sometimes I think students run it and then shut it off when the bucket is full. Are small batches not good for the system? What would be the amount of a small batch?
Tomorrow morning I will check carbon canister seals and look at flow restrictor and flush membrane. And check TDS between stages. And at the tap. I think it is really high, normally around 300 ppm.
No, I do not flush membrane every time. Should I? By removing flow restrictor and letting water pass through?
I would say we normally make 25-50 gal at a time. Maybe less on occasion. Sometimes I think students run it and then shut it off when the bucket is full. Are small batches not good for the system? What would be the amount of a small batch?
Tomorrow morning I will check carbon canister seals and look at flow restrictor and flush membrane. And check TDS between stages. And at the tap. I think it is really high, normally around 300 ppm.
Vhuang168
Guest
http://www.reefaddicts.com/content.php/182-RO-DI-TDS-Creep-is-it-worthy-of-concern
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Mozby
Guest
So should we flush everytime?
And is short cycling bad? I make 14-16 gallons once every 2 weeks. Is that short cycling?
MolaMola
Supporting Member
Holy crap. Not a fan of water today. During aqua class we measured TDS at various points in RO system. Changed out the seals on 2 carbon filters because one was rough and one was slimy. Couldn't find flow restrictor - was looking in the wrong place. Found it but cannot get the tubing off there because it is jammed in the fitting. I remember this happened last time, too. Stop there.
Then I had prep period with no kids. Decided to remeasure TDS in case it was carbon stage problem. Turned it on, went across the room while it got going again, heard and saw water spewing out of improperly connected tubing. Ran over, slipped on wet floor onto kneecap, heard CLICK as GFCI shut off big tank nearby plus extra power strip with powerhead. On other side, water dripped from cabinet onto power strip for quarantine tank, shutting that off. I turn off RO, now have wet shirt which is not appropriate for school, dry the entire area. Get tanks going again - thank goodness GFCI is not wet inside! Then notice the ink from wet student work taped to cabinet dripping into QT. Nice.
Still cannot get tubing and flow restrictor off. Will try after school.
So here's the measured TDS now:
Tap: 260
After sediment + 2 carbons: 264
After RO: 46
After single DI: 3
Shouldn't it be lower after sediment and carbons?
Then I had prep period with no kids. Decided to remeasure TDS in case it was carbon stage problem. Turned it on, went across the room while it got going again, heard and saw water spewing out of improperly connected tubing. Ran over, slipped on wet floor onto kneecap, heard CLICK as GFCI shut off big tank nearby plus extra power strip with powerhead. On other side, water dripped from cabinet onto power strip for quarantine tank, shutting that off. I turn off RO, now have wet shirt which is not appropriate for school, dry the entire area. Get tanks going again - thank goodness GFCI is not wet inside! Then notice the ink from wet student work taped to cabinet dripping into QT. Nice.
Still cannot get tubing and flow restrictor off. Will try after school.
So here's the measured TDS now:
Tap: 260
After sediment + 2 carbons: 264
After RO: 46
After single DI: 3
Shouldn't it be lower after sediment and carbons?
rygh
Guest
At least your kneecap did not go "click"
Sounds like a bad day...
Sediment does nothing to TDS. Just filters large particles.
Carbon does little, because most TDS is due to mineral content, and carbon does not affect that.
That does not mean it is not working. TDS is not a particularly good measurement of water "quality."
Carbon fines can increase TDS, although +4 could also just be margin of error in measurement.
That does seem a bit high after RO and DI.
KEY: let it run for a while. There is often a bit of accumulated crud.
For my brand new 6 stage:
Starts at 90+ after RO stage when first turned on, but drops to 10 in a few minutes.
Final output is always 0 though.
Sounds like a bad day...
Sediment does nothing to TDS. Just filters large particles.
Carbon does little, because most TDS is due to mineral content, and carbon does not affect that.
That does not mean it is not working. TDS is not a particularly good measurement of water "quality."
Carbon fines can increase TDS, although +4 could also just be margin of error in measurement.
That does seem a bit high after RO and DI.
KEY: let it run for a while. There is often a bit of accumulated crud.
For my brand new 6 stage:
Starts at 90+ after RO stage when first turned on, but drops to 10 in a few minutes.
Final output is always 0 though.
Vhuang168
Guest
[QUOTE="rygh, post: 334603, member: 911"
That does seem a bit high after RO and DI.
KEY: let it run for a while. There is often a bit of accumulated crud.
For my brand new 6 stage:
Starts at 90+ after RO stage when first turned on, but drops to 10 in a few minutes.
Final output is always 0 though.[/QUOTE]
That is tds creep. You should flush the RO for a few minutes to get rid of the high after membrane tds. This will save your resin life.
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That does seem a bit high after RO and DI.
KEY: let it run for a while. There is often a bit of accumulated crud.
For my brand new 6 stage:
Starts at 90+ after RO stage when first turned on, but drops to 10 in a few minutes.
Final output is always 0 though.[/QUOTE]
That is tds creep. You should flush the RO for a few minutes to get rid of the high after membrane tds. This will save your resin life.
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Mozby
Guest
That is tds creep. You should flush the RO for a few minutes to get rid of the high after membrane tds. This will save your resin life.
Sent from my iPhone using Tapatalk Pro[/QUOTE]
After watching videos about this, the logic seems sound. Interesting that the customer support agreed with it but downplayed it’s importance. They were saying “yes it’s true that there’s tds creep, but flushing/not flushing wont make a significant difference”. I find that hard to believe. Thoughts?
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rygh
Guest
After watching videos about this, the logic seems sound. Interesting that the customer support agreed with it but downplayed it’s importance. They were saying “yes it’s true that there’s tds creep, but flushing/not flushing wont make a significant difference”. I find that hard to believe. Thoughts?
Sent from my iPhone using Tapatalk[/QUOTE]
Well, we can do the math....
When I turn it on, around when barrel is half full, I usually run it for about 6 hours before it shuts itself off.
Lets say the base level is 10 ppm.
Lets say the average for the first 10 minutes is 75 ppm. (90, dropping to 10, have never graphed it)
So DI absorbs a base of 10 ppm * 6 hrs * 60 min/hr = 3,600 p
The DI absorbs a "creep" of 75 ppm * 10 min = 750 p
The units all cancel out, what really matters is the ratio.
750 / 3600 = 20%
So basically - I waste 20% of my DI resin by not flushing.
Of course, TDS only measures part of what is in the water. And I did make some very rough estimates.
But there is enough there to probably say : Not trivial, but not major.
rygh
Guest
Probably yes.
Also, I think they have better flow restrictors now.
Those old one were supposed to be trimmed.