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View Poll Results: how many min. do you flush the TDS creep | |||
2 min | 17 | 45.95% | |
3 min | 3 | 8.11% | |
4 min | 1 | 2.70% | |
5 min | 7 | 18.92% | |
6 min | 1 | 2.70% | |
other | 8 | 21.62% | |
Voters: 37. You may not vote on this poll |
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06/07/2016, 07:52 PM | #1 |
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time to remove TDS creep
I would like to get an idea on how long you flush your RO water for to remove TDS creep before letting it go into your DI, for me it takes about 4 min to drop my TDS from 534ppm to 4ppm.
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75 gal. mixed DT, 100 gal. sump, 50 gal. fuge, Clownfish breeder |
06/07/2016, 08:04 PM | #2 | |
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Quote:
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Quitters never lose. [QUOTE=CStrickland]Who gets mad at a starfish?[/QUOTE] Current Tank Info: 75g DT, 30G refugium, 10g chaeto tank, 50g stock tank basement sump |
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06/07/2016, 08:13 PM | #3 |
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yeah, why? does that seem like a long time?
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75 gal. mixed DT, 100 gal. sump, 50 gal. fuge, Clownfish breeder |
06/07/2016, 08:28 PM | #4 |
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Yeah it does dude. Mine will go from 100 or so down to 2 in a matter of seconds.
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Quitters never lose. [QUOTE=CStrickland]Who gets mad at a starfish?[/QUOTE] Current Tank Info: 75g DT, 30G refugium, 10g chaeto tank, 50g stock tank basement sump |
06/07/2016, 08:40 PM | #5 | |
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Quote:
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75 gal. mixed DT, 100 gal. sump, 50 gal. fuge, Clownfish breeder |
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06/08/2016, 12:57 AM | #6 |
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i dont normally stand there timing it but i would say i probably leave it flushing for about 5 mins. Well 5 mins flushing the waste line then about 1-2 mins flushing the product line before it goes through the DI.
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06/08/2016, 11:56 AM | #7 |
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I run 2-1 & Spectrapure suggests a 30 second flush.
I have doubled that on finish & start up.
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08/03/2016, 05:43 AM | #8 |
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Guys - make sure you understand the difference between:
1. A flush valve on the waste water line, and 2. A DI bypass They function very differently and are used for different purposes. Russ |
08/03/2016, 05:45 AM | #9 |
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08/03/2016, 06:06 AM | #10 |
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Usually 4 to 5 minutes here. I let it flush until the tds is down to about 10, post membrane, close the flush valve, then it takes another minute or so to drop down to 4. Which is when I close the secondary waste line and open the product line to let water start to enter the resin. Yes it takes a little more time, but my resin never sees more than 4 tds.
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08/03/2016, 06:18 AM | #11 |
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When you open the FLUSH VALVE, think about what happens to the net driving pressure on the membrane, and how that relates to the LOCATION of the TDS Creep water.
FLUSH VALVES on the waste water line are a terrifically inefficient way to deal with TDS Creep folks. |
08/03/2016, 07:46 AM | #12 | |
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Quote:
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- John New 260g build thread: http://www.reefcentral.com/forums/showthread.php?t=2557715 Current Tank Info: 260g reef, Giesemann Spectra MH/T5/Kessil A160, Dastaco CaRx, Vortechs, Lifereef skimmer, Red Dragon 3, Apex, Genesis, Angles, Tang, Trigger, Clowns, Anthias, Wrasses, Cardinals, SPS, LPS |
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08/03/2016, 07:49 AM | #13 |
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08/03/2016, 08:19 AM | #14 |
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He's saying using the flush valve is inefficient. And what you should be doing is running a DI bypass, thus allowing the RO membrane to work as normal until TDS creep is resolved, because the location of said TDS creep is in and around the membrane. A flush valve runs the RO membrane at a lower pressure, thus it ends up taking much longer to resolve TDS creep and you waste a bunch of water in the process.
Correct me if I'm wrong buckeye |
08/03/2016, 08:59 AM | #15 | |
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Maybe this will help: Think of two "sides" of the RO membrane. The HIGH Pressure side includes the high pressure feedwater reaching the RO element, going through the element, through the flow restrictor, and out the waste water tube. The LOW Pressure side of the membrane is the permeate - the "RO water." TDS Creep results from high TDS water on the LOW pressure side of the membrane. To get rid of this water it has to be pushed out of the permeate port. A Flush Valve is a Bypass of the flow restrictor on the HIGH pressure side of the system. A DI Bypass Valve is a way to temporarily divert the LOW Pressure Permeate away from the DI resin. When you open the Flush Valve, the pressure needed to move the TDS Creep water away from the membrane goes to nearly 0 psi. Use a DI Bypass Valve if you want to efficiently address TDS Creep. This is all pretty detailed wonky RO info, so I hope I didn't confuse folks... |
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08/03/2016, 09:20 AM | #16 |
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It all makes sense. Thanks for clarifying! I have been wasting water. one question then... what is the purpose of the flush valve??
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08/03/2016, 10:07 AM | #17 |
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Flush valve is to flush the membrane and membrane housing by allowing high flow water to rush through.
Not at all intended to address TDS creep issue. |
08/03/2016, 02:00 PM | #18 | |
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Quote:
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- John New 260g build thread: http://www.reefcentral.com/forums/showthread.php?t=2557715 Current Tank Info: 260g reef, Giesemann Spectra MH/T5/Kessil A160, Dastaco CaRx, Vortechs, Lifereef skimmer, Red Dragon 3, Apex, Genesis, Angles, Tang, Trigger, Clowns, Anthias, Wrasses, Cardinals, SPS, LPS |
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08/03/2016, 02:03 PM | #19 |
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"Waste water" is better thought of as "flush water." Its job is to remove from the RO element everything that doesn't go through the membrane. So flushing is a temporary boost in this flush water to clean the membrane and housing.
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08/03/2016, 05:55 PM | #20 |
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4-5 minutes here to go from 200+ to 4-5 ppm as well
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08/03/2016, 06:14 PM | #21 |
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I run a valve to bypass Di and send water to waste until TDS has dropped then switch the valve over it then goes through Di
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08/04/2016, 04:55 AM | #22 |
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I usually make about 2-5 gallons of RO water for drinking before RO/DI using the same 3 way valve that Buckeye posted
I also use an inline check valve between the membrane and the 1st DI to help with TDS creep |
08/04/2016, 07:10 AM | #23 |
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I generally flush mine for about 9 hours.
This has absolutely saved me from TDS creep while also single handidly destroying my wallet. Why you ask? because I'm an idiot and never remember because I'm like a golden retriever... squirrel!
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08/20/2016, 01:40 AM | #24 |
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We had a client with an RO system with two large commercial RO membranes they insisted on running at line pressure (meaning no high pressure pump). The combination of low feedwater pressure and lots of membrane surface yielded a TDS creep period that lasted over 5 minutes. Ugh.
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08/20/2016, 11:38 AM | #25 |
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I use my unit to make drinking water. This is taken off the DI bypass. I fill a few gallon jugs for drinking water then close the bypass to make tank water.
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