PPM has shot up from 2 to 11. Why?

[TimB]

Hi all, I run a 40/21 RO system, noticed a steady climb over the course of a week in my ppm to 10 so I replaced carbon and sediment filters to no avail. Then replaced resin and voila, perfect.

That was a month ago. My DI vessel is a big one, 10 litres plus easily, needed a quarter of a bag to fill.

It's just today shot up to 11 from 2 last time I did it. Only gone through about 4000 litres Inc waste so I'd love some input into what the hell has happened.

It comes out at 129 from the membrane. Both numbers shot up and then have sat there for a while before I turned it off.

Now, being tired and a bit of an idiot, I DID put the hose round the wrong way and so pumped water in the outlet valve of the membrane for like 30 seconds. Could that have upset something? Has the membrane gone? Can't call daqua right now, but that's where the kits from.

I'm buying in water for the rest of the week but need to sort it.

 

[Part Timer]

If the TDS is 129 after the membrane then there is a problem with that. What is your tap TDS because even an old membrane would remove 80% of impurities

 

[TimB]

If the TDS is 129 after the membrane then there is a problem with that. What is your tap TDS because even an old membrane would remove 80% of impurities

450 approx on the tap. I bought this setup second hand and the membrane is around 4 years old. Just seems strange that it jumped and then is holding steady at around 10 pure and 129 out of the membrane. Its not getting worse, although I've only run for a few mins.

If it were resin, or filters my understanding is that the numbers would steadily rise.

 

[ched999uk]

At best your membrane should remove 97 or 98% of the tds. So it's currently running at about 60% so as long as the pressure is high enough then the membrane is probably shot. How regularly do you flush it and for how long?

 

[TimB]

At best your membrane should remove 97 or 98% of the tds. So it's currently running at about 60% so as long as the pressure is high enough then the membrane is probably shot. How regularly do you flush it and for how long?

I flush before every use, which is about 2 or 3 times a week and for 5 mins each time.

 

[ched999uk]

I flush before every use, which is about 2 or 3 times a week and for 5 mins each time.

Does sound like the membrane is failing. There is a resin calculator on Grippa tanks site. Might be worth comparing the cost of your resin with 129tds vs a new membrane at even 97% efficiency (so about 14tds out). You might be surprised by how quick a new membrane would take to be cheaper than resin changes.
Double check your input pressure though before buying a new membrane and check the flow rates of pure vs waste just to check as a new membrane isn't cheap.

Doug would probably be best for advice.

 

[TimB]

Does sound like the membrane is failing. There is a resin calculator on Grippa tanks site. Might be worth comparing the cost of your resin with 129tds vs a new membrane at even 97% efficiency (so about 14tds out). You might be surprised by how quick a new membrane would take to be cheaper than resin changes.
Double check your input pressure though before buying a new membrane and check the flow rates of pure vs waste just to check as a new membrane isn't cheap.

Doug would probably be best for advice.

Thanks for the good advice. My pressure is good at 100 psi and the waste/pure ratio seems good to me. About 60/40 or 55/45. It puts out 2 litres pure a minute.

I'm happy to buy a new membrane, it's a good learning experience to fit one. I just want to make sure before spending that was all.

 

[ched999uk]

Thanks for the good advice. My pressure is good at 100 psi and the waste/pure ratio seems good to me. About 60/40 or 55/45. It puts out 2 litres pure a minute.

I'm happy to buy a new membrane, it's a good learning experience to fit one. I just want to make sure before spending that was all.

Just to be sure double check thinks like pressure and ratio as sometimes mains pressure does change or waste valves wear and allow more waste to flow.
You are right to double check things before shelling out.

 

[Part Timer]

Probably at a TDS of 129 then the resin won't get it down if it's running through quickly. You will be eating your resin so have a word with @doug atkinson and he'll talk you through what you require

 

[scottish cleaning service]

My membranes begun to fail after two years but I did let them freeze many times. Bought a pair of Axiom membranes which I believe are the best. Not sure how long they will last but hoping for 5 years.

 

[doug atkinson]

Flowing the water the wrong way does cause damage to your membrane. With it being 4 years old it will have dislodged all the sediment in the membrane sheets.

Try flushing for a good half hour and see if it drops. My gut feeling due to the age of the membrane it may not work.

 

[TimB]

Flowing the water the wrong way does cause damage to your membrane. With it being 4 years old it will have dislodged all the sediment in the membrane sheets.

Try flushing for a good half hour and see if it drops. My gut feeling due to the age of the membrane it may not work.

Thanks Doug. Think I'm going to just invest in a new one, that way everything eg filters resin and membrane will be new and i can feel more confident. Would it be a low pressure membrane I need do you think?

 

[scottish cleaning service]

Flowing the water the wrong way does cause damage to your membrane. With it being 4 years old it will have dislodged all the sediment in the membrane sheets.

Try flushing for a good half hour and see if it drops. My gut feeling due to the age of the membrane it may not work.

I did that as well so there was no hope for mine.

 

[doug atkinson]

Your pressure is good at 100 PSI so an HF4-4021 will be fine.

 

[spruce]

Hi all, I run a 40/21 RO system, noticed a steady climb over the course of a week in my ppm to 10 so I replaced carbon and sediment filters to no avail. Then replaced resin and voila, perfect.

That was a month ago. My DI vessel is a big one, 10 litres plus easily, needed a quarter of a bag to fill.

It's just today shot up to 11 from 2 last time I did it. Only gone through about 4000 litres Inc waste so I'd love some input into what the hell has happened.

It comes out at 129 from the membrane. Both numbers shot up and then have sat there for a while before I turned it off.

Now, being tired and a bit of an idiot, I DID put the hose round the wrong way and so pumped water in the outlet valve of the membrane for like 30 seconds. Could that have upset something? Has the membrane gone? Can't call daqua right now, but that's where the kits from.

I'm buying in water for the rest of the week but need to sort it.

Prefilters will make no difference to the ppm of your r/o pure output, as you have experienced. The prefilters are there to solely protect the membrane. The carbon block is especially important as it removes chlorine from the water. Chlorine and the membrane material aren't compatible as it eats away at it, slowly destroying it. This is why it is important to change the carbon filter to the manufacturer specifications.

I have 20" prefilters and use Fiberdyne carbon block filters. I change mine every 77k. I have a water meter on my r/o input, so I know when replacement is due. I replace the sediment filter at the same time.

Which reminds me @doug atkinson I need to order some prefilters from you.

 

[TimB]

Thanks all, a new membrane came through quickly.

Unfortunately the housing for the old one is a nightmare. Currently giving myself an aneurism trying to just open the thing.

 

[scottish cleaning service]

Thanks all, a new membrane came through quickly.

Unfortunately the housing for the old one is a nightmare. Currently giving myself an aneurism trying to just open the thing.

Use a hairdryer and it should expand it.