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RO Help - Membrane not lasting


Paul Symonds

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Paul Symonds

Hi,

Sorry, I don't post much but am in need of a bit of help.

I bought an second hand Xline System RO/DI last year but I seem to be going through membranes way too quick. I live in Southampton so the water quality is rubbish (reading 311 this morning) but it still doesn't seem to last as long as other peoples. It must be barely a year since I replaced it, it was a 4040 XLE Ultra low pressure membrane from Vyair. I have replaced the prefilters 3 times since then but maybe I don't change them enough as I'm not sure how often they should be changed. I use about 1200l pure water a week and the waste to pure water is set by xline and I think it is about 60:40 waste to pure. The system has an auto flush feature so flushes regularly. The TDS reading after the membrane now is at 89 ppm and so resin is being changed a lot.

So looking for advice.

Should my membrane be lasting longer?

How can I make it last longer?

Should I be buying a better quality membrane

How often shoud the prefilters be changed, they were Vyair ones and it just says they last 1-6 months on their site, not much help.

Should I have some sort of water softener of granulated carbon before the membrane? I've heard about this but not to sure of how to do it or the benefits.

Any advice would be great, especially from anyone in Southampton of how they do it? Thank you.

 

Edited by Paul Symonds
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I'm not familliar with your system but a 4040 membrane should last years so either you have been buying dodgy knock offs or something is killing them, most likely culprit I would guess is chlorine, ca

I recently purchased a second hand Merlin RO unit. I had to buy two new membranes and a new carbon block. My tap water is 270ppm. The new membranes started production at 130ppm at 40psi. I ran it for

To be fair you should be getting 000 out of the resin with a low figure of 005 from the ro , what size resin vessel do you have ?. Unless the TDS meter isn’t accurate.

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I'm not familliar with your system but a 4040 membrane should last years so either you have been buying dodgy knock offs or something is killing them, most likely culprit I would guess is chlorine, carbon pre-filters protect against chlorine but have a limited lifespan. Doug Atkinson would be the man for this one I think.

 

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11 hours ago, Paul Symonds said:

Hi,

Sorry, I don't post much but am in need of a bit of help.

I bought an second hand Xline System RO/DI last year but I seem to be going through membranes way too quick. I live in Southampton so the water quality is rubbish (reading 311 this morning) but it still doesn't seem to last as long as other peoples. It must be barely a year since I replaced it, it was a 4040 XLE Ultra low pressure membrane from Vyair. I have replaced the prefilters 3 times since then but maybe I don't change them enough as I'm not sure how often they should be changed. I use about 1200l pure water a week and the waste to pure water is set by xline and I think it is about 60:40 waste to pure. The system has an auto flush feature so flushes regularly. The TDS reading after the membrane now is at 89 ppm and so resin is being changed a lot.

So looking for advice.

Should my membrane be lasting longer?

How can I make it last longer?

Should I be buying a better quality membrane

How often shoud the prefilters be changed, they were Vyair ones and it just says they last 1-6 months on their site, not much help.

Should I have some sort of water softener of granulated carbon before the membrane? I've heard about this but not to sure of how to do it or the benefits.

Any advice would be great, especially from anyone in Southampton of how they do it? Thank you.

 

Whats your water pressure? This is an important question.

Have you physically checked what your waste to pure ratio actually is?

Everyone will tell you different stories on membrane care and what membrane to use. A cleaner I know uses the membrane you purchased with a booster pump and says he has good performance results. Someone else will say the same membrane is rubbish.

While the membrane is the most important part aspect in water purification, protecting that membrane against sediment and chlorine is also important.

I'm afraid Vyair don't give much technical detail that is of any use to anyone with regard to their products. This is one reason I don't deal with them. Just because they advertise this membrane as Ultra Low Pressure doesn't mean anything. (Its ultra low pressure when compared to a sea water reverse osmosis membrane which needs a pressure of 500 - 600 psi to operate.)

Some cheap carbon block filters only have a service life of 6000 liters of tap water. This includes waste and pure. If you are using 1200 liters of pure a week, you will be using approx 4800 liters a month of pure. If your pure to waste ratio is 60:40 then your r/o will be consuming 12,000 liters of water a month. We haven't included the additional flush water every time the auto flush activates.

If you have one of these cheap carbon filters you should be replacing it every 2 weeks. But here is the problem. How much chlorine is in your water? The carbon block filter is there to remove chlorine as chlorine damages membranes. The amount of chlorine in the water at the tap varies from area to area and apparently, how far away your house is from the dosing station. Some cleaners use cheap carbon block filters and only replace them every 6 months.

I operate my system with Fiberdyne carbon block prefilters. Mine are 20" and according to the manufacturers they have a service life of 75600 liters. I have fitted a water meter to my r/o so I know when the time is to replace my prefilters. I don't know how much chlorine is in my water supply. I presume that the service life given by the manufacturers is the maximum amount to sanitize our water for safe drinking laid out in the water regulations in America. (I did send the manufacturers an email asking this question but I didn't get a reply.) If the amount of chlorine is half that in my water supply then it could be the my Fiberdyne will last twice as long. But I have had excellent results changing the prefilter at the manufacturers recommended service life of 75600 liters or there abouts.

Our tap water tds is about 125ppm and this membrane has been in use for 8 years this month Its still producing water at 97% efficiency. Now it could be that if I lived in Southampton my membrane might not last as long if the tap water has a lot of calcium in it.

My water pressure is 50psi and I don't use a booster pump. I choose an Axeon HF5 low pressure membrane as I didn't want to use a booster pump using an HF4 membrane. I will replace it with another Axeon HF5 when the time comes provided there isn't anything better that comes along. Yes, they are much more expensive but I believe its saved me money in the long term.

In the early days of wfp I purchased a secondhand RoMan type r/o from a local window cleaner. It was 1 year old. He changed prefilters for the first time for me. Unfortunately, I had to replace the membranes as they were already 'shot'. I then replaced the prefilters every 3 months and those new membranes lasted me for 6 years before I upgraded to this 4040. I just applied this prefilter replacement schedule experience to maintaining my 4040.

My first stop is to deal with a recognised wfp supplier such as Daqua or GAPS Water. Doug at Daqua is very helpful and his focus is toward window cleaning applications.

You will notice that some other suppliers sell the same r/os to users wanting them for aquatics and drinks industry. These applications don't need efficient membranes and they often add another filter to make the water taste good. We need the most efficient membranes for window cleaning.

You will also notice that Window Cleaning Warehouse advertise  Axeon membranes. There is a note that they will supply either Axeon membranes or Spectrum membranes when you order an Axeon. I won't deal with them for membranes. If I want an Axeon then I don't want a Spectrum to be supplied instead as their choice.

However Daqua have stated recently that Spectrum have a new membrane which performs very well on first trails. Membrane longevity is still to be evaluated.

 

Edited by spruce
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Paul Symonds

Wow, thanks for the replies, especially Spruce, that is very in depth. 

Maybe I haven't been buying good yet enough prefilters and not changing them quick enough. 

 

How can I find out what the water pressure is? 

Also, what does the efficiency of the membrane mean? How do you work that out? Is it TDS in v TDS out? 

 

What's the best way to get in touch with doug at daqua? 

 

Thank you. 

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7 minutes ago, Paul Symonds said:

Wow, thanks for the replies, especially Spruce, that is very in depth. 

Maybe I haven't been buying good yet enough prefilters and not changing them quick enough. 

 

How can I find out what the water pressure is? 

Also, what does the efficiency of the membrane mean? How do you work that out? Is it TDS in v TDS out? 

 

What's the best way to get in touch with doug at daqua? 

 

Thank you. 

You can tag him in @doug atkinson https://www.daqua.co.uk/ro_systems.htmhe is very helpful. 

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doug atkinson
9 hours ago, Paul Symonds said:

Hi,

Sorry, I don't post much but am in need of a bit of help.

I bought an second hand Xline System RO/DI last year but I seem to be going through membranes way too quick. I live in Southampton so the water quality is rubbish (reading 311 this morning) but it still doesn't seem to last as long as other peoples. It must be barely a year since I replaced it, it was a 4040 XLE Ultra low pressure membrane from Vyair. I have replaced the prefilters 3 times since then but maybe I don't change them enough as I'm not sure how often they should be changed. I use about 1200l pure water a week and the waste to pure water is set by xline and I think it is about 60:40 waste to pure. The system has an auto flush feature so flushes regularly. The TDS reading after the membrane now is at 89 ppm and so resin is being changed a lot.

So looking for advice.

Should my membrane be lasting longer?

How can I make it last longer?

Should I be buying a better quality membrane

How often shoud the prefilters be changed, they were Vyair ones and it just says they last 1-6 months on their site, not much help.

Should I have some sort of water softener of granulated carbon before the membrane? I've heard about this but not to sure of how to do it or the benefits.

Any advice would be great, especially from anyone in Southampton of how they do it? Thank you.

 

Simple answer no it’s from Vyair. 

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2 hours ago, Paul Symonds said:

Wow, thanks for the replies, especially Spruce, that is very in depth. 

Maybe I haven't been buying good yet enough prefilters and not changing them quick enough. 

 

How can I find out what the water pressure is? 

Also, what does the efficiency of the membrane mean? How do you work that out? Is it TDS in v TDS out? 

 

What's the best way to get in touch with doug at daqua? 

 

Thank you. 

Its a pity you don't come on the forum much as this has been discussed in depth recently.

Water pressure is measured with a gauge which can be purchased from Screwfix or any other plumbing supply outlet.

https://www.screwfix.com/p/monument-tools-mains-water-pressure-test-gauge/82412

Yes, efficiency is the difference between the tap water tds and the pure after r/o but before di. Readings are taken when the r/o is in use for a while, probably after 10 minutes or so.Membrane efficiency or rejection rate is easy to work out.

If your tap water is 255 and your reject water is 5 then your rejection rate is 98%. (255 - 5 = 250 ÷ 255 = .98039 x 100 = 98%.)

When your membrane's performance drops to around 94% then its probably time to consider a new membrane.

Google is a good search engine.

 

Edited by spruce
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Paul Symonds

Thanks Spruce, yes Google is good but sometimes confusing if you don't understand everything. 

Thanks for the pressure meter. 

I've been looking at the fibredyne prefilters and axeon membrane. With the fibredyne some places say you don't need a sediment filter, is that how you run it? My sediment filter gets very brown (from rust I assume) so I think it's possibly worth still keeping one. 

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I use the fibredyne carbon filter, I buy them from Doug at Daqua. I still use a sediment filter beforehand though. 
 

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9 hours ago, Paul Symonds said:

Thanks Spruce, yes Google is good but sometimes confusing if you don't understand everything. 

Thanks for the pressure meter. 

I've been looking at the fibredyne prefilters and axeon membrane. With the fibredyne some places say you don't need a sediment filter, is that how you run it? My sediment filter gets very brown (from rust I assume) so I think it's possibly worth still keeping one. 

If your water is laden with sediment like ours sometimes is then yes you should keep it. There were times when our water was so bad that I was replacing a sediment filter twice before the carbon block was due to be replaced. It was cheaper to replace the sediment filter than a blocked Fiberdyne filter.

Our water quality is better now so I can get away with replacing both together. I have a pressure gauge on each side of the prefilters so I can monitor how clogged up the sediment filter becomes. Our water pressure is 50psi and when the output from the prefilters drops to 40psi I change the sediment filter.

On my old 450gpd r/o I got caught once. I replaced prefilters the evening before and the next evening the sediment filter was blocked up so had to be changed again. When I ran the cold tap into the bath it was red with sediment. 

I now know the water pipe layout in our estate that could effect me. If I see them working on the pipes before our house I switch my r/o off until I see the bath water test is clear.

If you have 10" filters the 10" Fiberdyne filter has 1/2 the service life of a 20" one.

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9 hours ago, spruce said:

If your water is laden with sediment like ours sometimes is then yes you should keep it. There were times when our water was so bad that I was replacing a sediment filter twice before the carbon block was due to be replaced. It was cheaper to replace the sediment filter than a blocked Fiberdyne filter.

Our water quality is better now so I can get away with replacing both together. I have a pressure gauge on each side of the prefilters so I can monitor how clogged up the sediment filter becomes. Our water pressure is 50psi and when the output from the prefilters drops to 40psi I change the sediment filter.

On my old 450gpd r/o I got caught once. I replaced prefilters the evening before and the next evening the sediment filter was blocked up so had to be changed again. When I ran the cold tap into the bath it was red with sediment. 

I now know the water pipe layout in our estate that could effect me. If I see them working on the pipes before our house I switch my r/o off until I see the bath water test is clear.

If you have 10" filters the 10" Fiberdyne filter has 1/2 the service life of a 20" one.

I think I need to get some pressure gauges on my system. I have one before the ore filters that tells me my water pressure, then that’s it. I think I could do with a couple of tweaks. It all helps to keep things good and running smooth. It is frustrating though at times, I’ve given my system a good hours flush over the weekend and after my membrane before resin my TDS is now 4. I can’t understand it at times. I’m going to do what Doug suggested buy some vodka and clean the probes of the inline TDS meter. If it does t send me to drink first. 🤣

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30 minutes ago, Jango said:

I think I need to get some pressure gauges on my system. I have one before the ore filters that tells me my water pressure, then that’s it. I think I could do with a couple of tweaks. It all helps to keep things good and running smooth. It is frustrating though at times, I’ve given my system a good hours flush over the weekend and after my membrane before resin my TDS is now 4. I can’t understand it at times. I’m going to do what Doug suggested buy some vodka and clean the probes of the inline TDS meter. If it does t send me to drink first. 🤣

When my tds after r/o goes to 4 then its usually the tap water tds that's gone up.

A while back my tds meter read 1ppm out for the di vessel where my tds meter read 0. My tds meter was calibrated with a bottle of tds fluid I purchased a while back from RoMan.

So is my tds meter right or my inline tds meter?

Segal's law states:

"A man with one clock knows what time it is. A man with two clocks is never sure."

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11 minutes ago, spruce said:

When my tds after r/o goes to 4 then its usually the tap water tds that's gone up.

A while back my tds meter read 1ppm out for the di vessel where my tds meter read 0. My tds meter was calibrated with a bottle of tds fluid I purchased a while back from RoMan.

So is my tds meter right or my inline tds meter?

Segal's law states:

"A man with one clock knows what time it is. A man with two clocks is never sure."

It’s before DI I have 4 it was 11 on Friday. That’s why I’m nearly on the vodka. Coming out of DI at 2. If I test with handheld meter it’s 1. I agree with the above. You just at times get frustrated with it. So you double check then more confusion. 

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1 hour ago, Jango said:

It’s before DI I have 4 it was 11 on Friday. That’s why I’m nearly on the vodka. Coming out of DI at 2. If I test with handheld meter it’s 1. I agree with the above. You just at times get frustrated with it. So you double check then more confusion. 

Tds creep can play havoc with readings. This is why its important to let the r/o produce water for a period of time before taking readings.

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18 hours ago, spruce said:

Tds creep can play havoc with readings. This is why its important to let the r/o produce water for a period of time before taking readings.

Yes I have been doing this but it’s constantly changing it’s really strange. It’s been coming out of the membrane  before DI at 11tds for over a year. But the last two weeks it’s gone up to 12 then dropped to 4 after a couple of days now today it’s 7. 
when you speak about the pressure gauge do you have one after each filter. I have one before the water enters the filters telling me the pressure. Should I put another in between the sediment and before the fibredyne, or after the fibredyne before the membrane. Where does one go on the membrane? Many thanks. 

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20 minutes ago, Jango said:

Yes I have been doing this but it’s constantly changing it’s really strange. It’s been coming out of the membrane  before DI at 11tds for over a year. But the last two weeks it’s gone up to 12 then dropped to 4 after a couple of days now today it’s 7. 
when you speak about the pressure gauge do you have one after each filter. I have one before the water enters the filters telling me the pressure. Should I put another in between the sediment and before the fibredyne, or after the fibredyne before the membrane. Where does one go on the membrane? Many thanks. 

The only one I have is on the membrane and it sits on top of the membrane

20200715_142704.jpg

Edited by Part Timer
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47 minutes ago, Part Timer said:

The only one I have is on the membrane and it sits on top of the membrane

20200715_142704.jpg

Ok thank you. There is one on the top of my membrane but it doesn’t work so I could do to get that replaced. 

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3 hours ago, Jango said:

Yes I have been doing this but it’s constantly changing it’s really strange. It’s been coming out of the membrane  before DI at 11tds for over a year. But the last two weeks it’s gone up to 12 then dropped to 4 after a couple of days now today it’s 7. 
when you speak about the pressure gauge do you have one after each filter. I have one before the water enters the filters telling me the pressure. Should I put another in between the sediment and before the fibredyne, or after the fibredyne before the membrane. Where does one go on the membrane? Many thanks. 

I wouldn't. Its always been the sediment filter that get blocked with mine. The sediment filter is 5 micron so anything smaller passes through it to begin with. But once the filter gets clogged up everything gets blocked including water.

The Fiberdyne is 5 to 10 micron so it will never get blocked.

As I say, our water pressure is 50psi. When the sediment filter get clogged up the flow through it reduces and the pressure drops. When the pressure drops to 40psi I will change the sediment filter. If they are all just about due then I will replace both. At 40psi my tds output will go up from 3ppm to 4ppm.

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14 hours ago, spruce said:

I wouldn't. Its always been the sediment filter that get blocked with mine. The sediment filter is 5 micron so anything smaller passes through it to begin with. But once the filter gets clogged up everything gets blocked including water.

The Fiberdyne is 5 to 10 micron so it will never get blocked.

As I say, our water pressure is 50psi. When the sediment filter get clogged up the flow through it reduces and the pressure drops. When the pressure drops to 40psi I will change the sediment filter. If they are all just about due then I will replace both. At 40psi my tds output will go up from 3ppm to 4ppm.

Thanks for the info. 
I have just found out last week they have been doing some work in our road with the water. So maybe this weekend I should flush the system for a few hours. No doubt that’s the problem in the fluctuations. 

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On 13/07/2020 at 16:59, Paul Symonds said:

Wow, thanks for the replies, especially Spruce, that is very in depth. 

Maybe I haven't been buying good yet enough prefilters and not changing them quick enough. 

 

How can I find out what the water pressure is? 

Also, what does the efficiency of the membrane mean? How do you work that out? Is it TDS in v TDS out? 

 

What's the best way to get in touch with doug at daqua? 

 

Thank you. 

https://www.amazon.co.uk/Silverline-482913-Mains-Water-Pressure/dp/B06XY8WPYS/ref=mp_s_a_1_3?dchild=1&keywords=water+pressure+gauge&qid=1594918432&sprefix=water+pre&sr=8-3

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