RO Membrane - Huntsville water

[pickupman66]

just going to say this for the sake of arguement, but do you think that red light green light indicator is malfunctioning?

 

[H@rry]

just going to say this for the sake of arguement, but do you think that red light green light indicator is malfunctioning?

No, the color changing DI resin changes to halfway down the cartridge in a week or so. The more I think about it I believe excessive flushing ruins the carbon filter and then chlorine destroys the membrane.

And Lindsey, since you brought it up, why would you want to argue with me? Didn't 'yo mama tell you 'bout respectin' 'yo elders? eace:

 

[Buckeye Field Supply]

Hold on a minute here. If I'm reading you right the color change starts at the TOP of your DI cartridge, right?
And this is a refillable cartridge, right?

 

[H@rry]

Hold on a minute here. If I'm reading you right the color change starts at the TOP of your DI cartridge, right?
And this is a refillable cartridge, right?

Right and right.

 

[Buckeye Field Supply]

Ding, Ding, Ding. I think we have an answer folks! Your refillable cartridge, assuming it looks like this:



is an UPFLOW cartridge. Given that, you should start to see the color change at the BOTTOM of the cartridge first.
When the top portion of the cart changes color first, it typically means that the resin was not packed tightly enough in the cartridge to start out with, the DI bed has fluidized, and the cation beads and anion beads have separated. When this happens, the DI water TDS will typically go up a few ppm - if I'm right this is what is triggering your green light/red light conductivity meter.

So:
1) check to see if there is any free space in the cartridge. I'll bet there is. If so:
2) dump the resin out into a very clean glass bowl and remix the cation and anion beads.
3) repack the cartridge and add more resin - pack it as tight as possible.
4) run some more DI water and see what your indicator tells you.

(and by the way - get a TDS meter!)

Russ

 

[H@rry]

Russ, I think you're right about it not being packed tight enough. When I change it I notice that the sponge which was on the screw-on end has "migrated" to the top. I'll check that out. Thanx a lot.

 

[pickupman66]

Don't make me come down to Huntsville and show u how to use a TDS meter!

sent from my old fashioned Galaxy tab with Tapatalk 2

 

[H@rry]

Come on down and test it. I'll give you a frag for the trouble.

 

[Tomoko Schum]

It does not make sense to me, Harry...

I thought that the water travelled through an RO system in the same way whether you use a flush valve or not. A flush valve simply open up a second unrestricted route for water to exit the system fast. The water travels through all the prefilters and hits the outside of the membrane instead of going through the membrane since there is no pressure buildup to force the water through the membrane.

As for the resin turning the color backward, I experienced that when I inadvertantly inserted the tubing backward putting the output of the RO system into the outlet side of the DI resin cartridge. The TDS reading of the DI cartridge output water started creeping up as well like the resin was spent although the DI resin color changed only down to the midway. The water was travelling through only the upper part of the DI cartridge (a shorter and the easiest route) instead of going through the entire length of the cartridge. When I inserted the tubes correctly with the next batch of resin, the color change reversed and the resin lasted as expected.

By the way, I got the lastest drinking water report from Madison Utilities. The report lists the chloramine level to be 4 ppm. Bulk Reef Supplies maintains a database of municipalities using chloramine. According to the database (last updated Dec 2012) Huntsville is now using chloramine (Chloramines Database - Bulk Reef Supply.)

 

[H@rry]

Tomoko, that would answer the question of what is causing the membrane to be depleted so quickly. But, the BRS chart for Huntsville lists a phone number for area code 936. That is Huntsville, Texas so I wouldn't put much faith it that chart. I just called Huntsville Utilities Water Quality Lab and talked with a lady who told me that they used chlorine and "bleach". She said she knew what chloramine was but Huntsville did not use it. She took down my name and number and said the person who was in charge of water quality will call me in the morning.

 

[Buckeye Field Supply]

Fun FAct for the day: TFC membranes (the type used in this hobby) are much more tolerant of chloramines than chlorine.

Russ

 

[Tomoko Schum]

I hope she is right. Madison has started using chloramine obviously.

>>Tomoko, that would answer the question of what is causing the membrane to be depleted so quickly<<

I am still not sure how that is so. Your RO membrane is rinsed with Chlorine free water since the water goes through a sediment filter and two activated carbon filters before it hits the exterior surface of the membrane. Do you think that the frequency and the length of flushing has been excessive to cause a surface abrasion? Could it be a cavitation effect of a forceful water flow in-between the memrane and its housing that is making the membrane to fail prematurely? I recently saw an aftermath of severe cavitation inside a copper pipe that cause an erosion-corrosion, resulting in leaks from the pipe.

Whatever the cause may be, I suppose you can try reducing the frequency and the length of flusing to see if that helps.

 

[H@rry]

My theory is that the long flush period (5 - 15 minutes) allows so much water through the carbon filter that it depletes the carbon, which then allows chlorine to damage the membrane. This time I won't flush and see if it is any different.

 

[Tomoko Schum]

Oh, that makes sense

Chloramine is easier on the polymer material used on RO membranes as Russ pointed out, but the release of a small amount of freed ammonia can use up expensive DI resin faster. I need to consider the use of catalytic carbon since I get water from Madison Utilities.

 

[H@rry]

I just spoke with Jim Reynolds @ Huntsville Utilities Water Quality Lab. He said that Huntsville does not use chloramine and to his knowledge no water system in the state of Alabama does.