RO membrane life?

[Whipples]

Have you pulled the output lines and made sure you don’t have any blockages? Checked all plumbing for a piece being in the wrong spot? It seems silly I know, but it happens! Is there a check valve installed incorrectly?

 

[LiquidFunk]

Well it is a capilary restrictor, so unless part of the tube spontaneously broke off and went down the drain it is the same restrictor it was before.

Not sure how it would clog being down stream of the prefilters, so how could it have “gone bad”?

It produced water as expected on a new membrane and got progressively worse. Not sure how a flow restrictor would behave this way.

I did buy another, I swap it out prior to the membrane and see if it changes the product water.

I’ll also dig around for another TDS meter, or grab a HM one for $20 on amazon.

 

[LiquidFunk]

Does anyone know how a membrane behaves when chloramines ruin it? Does it “clog” or does it start passing more TDS?

 

[Whipples]

Chloramines will eat holes in the membrane causing rejection and psi to go down, and waste ratio to go closer to 1:1

 

[Whipples]

You’ve got an interesting scenario on your hands, I would maybe reach out to a local commercial fish tank company, like the kind that service tanks for large offices/buildings or even a plumber to see if they can help you get to the bottom of it assuming our suggestions don’t fix it. Can you get your water company’s quality report?

 

[LiquidFunk]

You’ve got an interesting scenario on your hands, I would maybe reach out to a local commercial fish tank company, like the kind that service tanks for large offices/buildings or even a plumber to see if they can help you get to the bottom of it assuming our suggestions don’t fix it. Can you get your water company’s quality report?

I am on a first name basis with every Aquarium business in the area, none of them are qualified to answer this issue. (They are my customers)

I’ll check with the municipality, they should certainly have a water expert that would have a suggestion. Thanks for the idea.

I have not suspected chloremines because I was under the same impression you are, that it would reduce the rejection water discharge rate and let more TDS through the membrane. That is not what is happening here it’s more like the membrane is clogging, which I don’t know anything that does that.

 

[LiquidFunk]

Anyone else have any thoughts on the matter?

 

[Bayareareefer18]

It is probably 1:200, I have a 100gpd membrane producing water via drips every 5-10 seconds. Certainly not what it did when it was new. To be clear I have been in this hobby professionally for 14 years but I have never come across RO membranes “clogging”. I am very aware of what kind of flow is typical for a 100gpd and I am no where near it. It’s only been an issue at my newer residence on different municipal water.

I have not tested for chloremines, nor am I using a chloramine specific carbon prefilter.
PSI is about 65.



Membrane is shot because my rejection rate is probably 200:1. I am not producing RO water. The rejection rate is typical, a steady pressurized stream out of the 1/4” line.

It takes a week to fill a 55gallon drum, while wasting thousands of gallons.

My TDS meter is shot, but I probably have a handheld around. My incoming TDS is around 600 when I tested it a few years ago. (Which sucks, my old house has single digit TDS)


Oh and lastly, I have checked my flow restricter and it appears fine, it’s the capilary style on the ejection line. It acts like I don’t have one. I purchaed a new one with my membrane which is due to land in 2 days.

I have the same unit. My understanding is the dual carbon filters are supposed to remove chloramine

I ordered the booster kit on Amazon since BRS was out. Boosts my pressure up to 80 psi.

Production water is very good. Was much slower prior

Don't know if that answers your issue...

Just throwing an idea out

 

[Forsaken77]

I am on a first name basis with every Aquarium business in the area, none of them are qualified to answer this issue. (They are my customers)

I’ll check with the municipality, they should certainly have a water expert that would have a suggestion. Thanks for the idea.

I have not suspected chloremines because I was under the same impression you are, that it would reduce the rejection water discharge rate and let more TDS through the membrane. That is not what is happening here it’s more like the membrane is clogging, which I don’t know anything that does that.

This is what I have noticed in my own personal experience. You know how the membranes say to run at 77° F, blah blah blah? I had my water connected to both the hot and cold of my washing machine and ran approximately 77° through the system.

Seeing BRS just run cold water through there's, I started doing that. It ended up dropping my psi and clogging my membrane faster.

I switched back to the warmer water with the same membrane that is 2 years old, and slowly my psi began to rise and product water was again increasing.

I did this because I noticed a lower tds before even hitting the sediment filter with just cold water. Once hot water was mixed in, the tds rose. But straight cold water caused problems with the membranes rejection rate and was acting like it was clogged. I even posted a thread here about how the pressure could drop so suddenly, but it was due to the cold water only. Maybe is was causing scaling or whatever. I even thought my restrictor was bad.

Btw... I would not recommend the capillary restrictors unless you have a complete bypass set up to flush with. They can also clog without notice. Using the restrictors that can be turned on and off with a lever is a lot easier, ime.

This is just my experience and may be applicable to your situation.

I know this is novice, but check for leaks, make sure no valves are in the wrong positions or bypasses left open. Sometimes the most simple things are the ones overlooked. A fitting may have gotten clogged leading to the membrane. I would replace things leading to the membrane before the actual membrane. Because going through them like that means the problem doesn't lie with the membrane.

 

[LiquidFunk]

Gents, I had a thought. I wonder if I was sent the wrong flow restrictor if that would then clog a membrane. Perhaps it was restricting too much thus forcing more waste into the membrane thereby clogging it.
Possible?

It’s a 100gpd membrane, and the flow restrictor is black and about 5” long. Anyone know what it’s supposed to look like?

I already replaced it with the valve style for flushing, but would help put my mind at rest if it was wrong.

 

[Whipples]

That sounds like it is extremely long. If you are using the capillary style, it needs to be trimmed to size based on output. More PSI = shorter restrictor tube. On my 150GPD setup at 100 PSI my capillary restrictor is set at ~2MM to maintain 3:1 waste : product ratio which will vary a bit setup to setup but its based on product water output. See page 11 of the pdf in the link below. While its a Spectrapure guide (what I run) the premise and function is the same. Maybe that was part of the problem?

https://spectrapure.com/manuals/memRepGuide.pdf

 

[Buckeye Hydro]

Careful here guys... there's a fair amount of info in this thread that's not quite on the money.

Russ

 

[Rst]

Thanks Greybeard, I appreciate it. You're right, 6 months is a bit of a generalization. They may last shorter or longer periods of time. You could be more smart about it and replace as needed, but it requires testing and diligence.

To know when the prefilter needs to be replaced, you have to monitor pressure before and after the prefilters. When there's a pressure drop, at least the prefilter needs to be replaced. Depending on the quality and size of the prefilter, the carbon blocks may need to be replaced too, as they can plug up with small particulate matter also.

To know when the carbon blocks need to be replaced, really the only good metric that I know of is chlorine breakthrough. If you test your membrane waste water and find any chlorine or chloramines, your carbon blocks need to be replaced immediately. You mentioned you don't have chlorine because you're on well water, but for all other reefers, chlorine will ruin an RO membrane in very short order, so it's sort of a "stop everything and replace this filter before making any more water" deal, which can be pretty inconvenient.

If a reefer is willing to deal with the hassle of testing the pressure and chlorine/chloramine breakthrough, then the 6 month rule doesn't apply. You'd probably save a lot of money replacing when you need to as opposed to just blindly replacing every six months (this is what I do, I test and replace as necessary). But, it requires constant vigilance or you're going to potentially fry your RO membrane (again, for those with chlorine/chloramine in their water).

I would like to test my waste water to tell when to change out my carbon block. Can you please recommend a suitable test kit when testing my waste water for chlorine/chloramine ? Some of the test kits I have seen are quite expensive. Do I change my carbon block when the ppm reaches say 0.1 ppm or can I let it go a bit higher before change outs? Thanks

 

[Buckeye Hydro]

Low cost Test Kit: http://www.buckeyehydro.com/insta-test-free-and-total-chlorine-test-strips/

Your Filmtec membrane has a chlorine tolerance of about 1000 ppm hours.

Russ

 

[theMeat]

Sounds like it’s the membrane.
It’s a good idea to change auto shut off, and flow restrictor when you change the membrane.

Lotsa good info in this thread

The auto shut off works on hi/low pressure. When the valve on the product line is shut it can take a minute or three to shut off the unit. If not it faulty, or installed wrong

To answer your question.
If the system is set up right and cartridges changed regularly the membrane should last at least 2 years. Have had membranes last 5+