[Afterglow Window Cleaners]

Hi Guys,

I have a pretty run of the mill 300GPD RO

My input water has a TDS of around 390ppm at the moment.

Water after prefilters the TDS is the same.

Water after membranes has shot up in the last few days and reads 40 -60 TDS.

I have tried cutting back to one membrane and still getting 30-40 TDS.

The membranes are connected in series, my RO is pumped and has the original flow restrictor from when the system was 100GPD, so does the flow restrictor need changing too?

I'm pretty sure this means my membranes have had it, but I'm no expert so any advice would be appreciated.

Thanks, Gary

[AuRavelling79]

How long have you been running these membranes?

How old are the prefilters?

How much pure water do use every week?

[easycleaner]

Hi.
The pre filters don't alter the TDS they look after the RO membranes.
With the TDS after the membranes it sound like they shop.
Mart

[Afterglow Window Cleaners]

Membranes are approx 15 months old, pre filters are new, I use about 1800 litres a week, cheers

[AuRavelling79]

Sometimes prefilters get "clogged", reduce flow and affect TDS.

I would say at 15 months and 1800 litres a week and input TDS at 300+ then you've had a good life out of your membranes.

I buy mine from Soap National as they seem to be consistently ok and cheaper than others.

I also upgraded (from 200 to 300) about three years ago but didn't change the restrictor and all seems well.

[Afterglow Window Cleaners]

Thanks for your help, I think upgrading from 200 to 300 uses the same flow restrictor as long as the membranes are in series.

What I am considering doing is getting 2 x 150gpd membranes instead of 3 x 100gpd so I would need a different flow restrictor?

The reason I am thinking this is the waste from each membrane in turn gets considerably worse from what I have read, so by the time my water is entering membrane 3 its really really bad quality.

I'd not heard of soap national so will take a look,

Thanks again, Gary

[Afterglow Window Cleaners]

Ok, so I fitted two new 150gpd Axeon membranes and new 150GPD flow restrictor from Daqua today, my TDS after RO (before DI) is still 30ppm (input water 390ppm), I was expecting well under 20ppm after RO, the system has been running a few hours so should have flushed the membranes by now.

If anyone can give me some advice on why the TDS is so high after RO, I would appreciate it

[sunshine windows]

With a booster pumped 450 gpd  system, approx 350 tds my water out of RO is 5, so something doesn't sound right.

Sorry I can't help though, useless at this technical stuff

[Afterglow Window Cleaners]

My RO output water is down to 22ppm now, so I assume they are still flushing a bit of the preservative chemical out.

I did a 3 hour flush today and it made next to no difference to the output TDS.

Is this a normal output for a 300gpd RO with my input water at 390ppm as I read a few sites that say output TDS should be between 5% and 7% of input TDS.

Thanks, Gary

[ian1965]

Are you using a water softener?
 

[Don Kee]

Just scrolled through the thread and I cant see anywhere you've posted about your water pressure?
So, do you have a pressure guage, and do you have a booster pump fitted?
Also what was your tds normally before it 'went up'

I'd also fit another 150gpd membrane (so you'll have 3 making it a 450gpd r.o)

[Afterglow Window Cleaners]

No water softener being used, would that help a lot?

I do use a booster pump and have a pressure guage which is not inline at the moment, I will fit it again and check pressure tomorrow, I remember my TDS after RO being less than 10, but I have not checked it in ages, the reason I checked it now was because my resin use has gone up significantly, (using 4x as much resin as before with my double DI setup)

Thanks for all replies so far