[Steve Weatherley]

I purchased the above mentioned RO system in June 2010. At the beginning it was bringing my TDS down from 280 to 19. I was pleased with this as I have a low pressure in of 40psi.
Unfortunately after less than a year it deteriorated and suddenly the TDS was around 100.
I had been neglectful when it came to regular changes of the pre filters and was told that this was probably the reason. So I bought a replacement in May 2011 and started to diary regular pre filter changes every 3 months.
Again after only 10 months I had the same problem and had to replace it again in March this year. Now already after only 8 months my readings are up to 55 and rising.
I am losing faith in these filters. Can anyone suggest a good alternative and also has anyone else had similar problems with these membranes?

I need to produce about 400 litres of pure water into my static system in under 6 hours and am considering a 450GPD smaller system with a booster pump.

[Lee GLS]

You must have a problem somewhere. I have one and it 2.5 years old, tds in 375 out 12.

Do you flush it regularly?

[Mike55]

Hi Steve,

Sounds like you have got the right tool for the job.  HF5 membrane is for lower water pressure.

Are you regularly flushing your RO?

[Spruce]

What prefilters are you using, especially the carbon filter?

[lozsing]

I damaged my 4040 membrane when I left it stood for 2 weeks whilst on summer holiday . When I came back ppm shot up to 170 then settled down to 50 so ended getting new as resin was only lasting 2 weeks in an 11 L bottle. Must have built up some bacteria in those 2 weeks because it was quite warm at home whilst I was away. Been wfp 3 years and it was the only time it had been left that long so it's the only reason that I can think of that caused it .

[Steve Weatherley]

Thanks for all your suggestions. I will answer your comments.......

The carbon pre-filter is a 10" one supplied by GAPS water supplies

I flush the RO every time before I switch on the water and flush it for about 3 minutes before filtering. I asked GAPS if this was the right thing to do and they said yes - no need to flush the system once a week for 30 mins like some other systems.

Suggestions by GAPS are:
Clean all housings and tubes with mild solution of bleach - as the membranes are only lasting less than a year it's possible that algae might have built up in the membrane housing
Change my pre-filters every 4-6 weeks

[Frankybadboy]

where did you buy the membrane from?

[Spruce]

Thanks for all your suggestions. I will answer your comments.......

The carbon pre-filter is a 10" one supplied by GAPS water supplies

I flush the RO every time before I switch on the water and flush it for about 3 minutes before filtering. I asked GAPS if this was the right thing to do and they said yes - no need to flush the system once a week for 30 mins like some other systems.

Suggestions by GAPS are:
Clean all housings and tubes with mild solution of bleach - as the membranes are only lasting less than a year it's possible that algae might have built up in the membrane housing
Change my pre-filters every 4-6 weeks

Steve,

Maybe talk to Perfect Windows on here as he has the same issue and strongly believes his problem is chlorine related so has gone to great lengths to suss this out.

I have a new 4040 with 20" prefilters. When I opened the GAC-20R-C is see that for the first time the label informs me that the service life is 2,500 GAL. I presume that these are American Gallons. If you have have your r/o pure to waste ratio set at 50/50 then you will only be able to produce around 5000 litres of pure water. The equivalent carbon block filters are even worse.

I ended up talking to Osmotics and they suggested that this was the filter to buy, which I did.

http://www.osmotics.co.uk/products/Pentek-ChlorPlus-Carbon-Block-Filter-20%22.html

I also asked the question of GAPS but didn't get a reply from June.

Vin has incorporated a di vessel full of charcoal which he hopes will kill the chlorine issue he believes is causing his membranes to fail prematurely. What does bug me a bit is that if there is a little chlorine leaking past the prefilters damaging the membrane, then it should also keep the bacteria away.

Perfect Windows is Onionman on another site.
http://w w w.cleaning forums.co.uk/viewtopic.php?f=2&t=6384

(Remove the gaps )

[Alex Gardiner]

I purchased the above mentioned RO system in June 2010. At the beginning it was bringing my TDS down from 280 to 19. I was pleased with this as I have a low pressure in of 40psi.
Unfortunately after less than a year it deteriorated and suddenly the TDS was around 100.
I had been neglectful when it came to regular changes of the pre filters and was told that this was probably the reason. So I bought a replacement in May 2011 and started to diary regular pre filter changes every 3 months.
Again after only 10 months I had the same problem and had to replace it again in March this year. Now already after only 8 months my readings are up to 55 and rising.
I am losing faith in these filters. Can anyone suggest a good alternative and also has anyone else had similar problems with these membranes?

I need to produce about 400 litres of pure water into my static system in under 6 hours and am considering a 450GPD smaller system with a booster pump.

HF5 membranes are great items but they do need to be treated properly to last. The membrane film in them is packed much more densely than the similar HF4 membranes. Whilst this does allow for greater production from lower water pressure and in colder climates, it does mean that they can become blocked more quickly in use.

As you have mentioned that you change your pre-filters regularly then this problem should not be chlorine related (although it may be). Ideally commercial grade membranes like this need much larger and longer-life carbon filters than a 10" filter, or even a 20" can offer.

I would imagine that on an input water of 280ppm your membranes are simply becoming either blocked up or mineralised-up from hard water. The solution would be to either fit a water softener before the RO or to flush for longer periods of time whilst in use. I would recommend flushing for at least 5 mins before each fill with either a 5 minute flush after each hour of production or a weekly flush of 30 minutes (5 mins every hour is better though).

The HF4 membrane whilst needing a higher input water pressure (50psi and above) will generally produce more water and will have a longer life due to being less densely packed inside.