RO system tds problem

[Purpule Tang]

Hello,guys.
I have 6 stage Ro system( 1 sediment 5 micron 2 carbon 3 carbon block 4 75 gallon dow filmtec membrane 5 post carbon 6 mineral filter).
But recently have a problem with outlet tds from membrane.
Our tap water tds with HM tds_3 meter is 360 ppm and outlet water from membrane is 85_87 ppm.
That's mean is my Ro system membrane need to change?
Pls help me,
Thanks,[emoji4]

 

[ReeferMaddness843]

Once the tds began to creep up on my tank water, I replaced all resins and filter blocks. Immediately back down to 000ppm

 

[ReeferMaddness843]

How is your output water pressure as well as the usable to wastewater ratio?

 

[Purpule Tang]

Once the tds began to creep up on my tank water, I replaced all resins and filter blocks. Immediately back down to 000ppm

I replaced all 3 pre filter but not changed my tds output membrane.

 

[Purpule Tang]

How is your output water pressure as well as the usable to wastewater ratio?

Excuse me your mean is pressure gauge on my Ro system?if yes it on between 60_70 psi.

 

[twilliard]

@AZDesertRat come on in!

 

[AZDesertRat]

Yes your RO membrane is not working as it should.
If your tap TDS is 360 you should bee seeing no more than 10 TDS in the RO only water.
Are you drawing water directly from the RO membrane for the TDS test? I am struggling to decipher your filter selection though. You say you have a 5 micron sediment filter, then two carbons but what are the micron ranges? Then the RO membrane and what is it you have after that? I would expect to see a DI filter but thats not what you described?
Have you measured your exact actual waste ratio? Too often people assume it is correct and honestly it rarely is. If you don't have the proper waste ratio a membrane doesn't last long.
Is your TDS meter accurate? Do you triple rinse it in RO/DI or distilled water after each use and put it away clean and capped?

 

[Purpule Tang]

Yes your RO membrane is not working as it should.
If your tap TDS is 360 you should bee seeing no more than 10 TDS in the RO only water.
Are you drawing water directly from the RO membrane for the TDS test? I am struggling to decipher your filter selection though. You say you have a 5 micron sediment filter, then two carbons but what are the micron ranges? Then the RO membrane and what is it you have after that? I would expect to see a DI filter but thats not what you described?
Have you measured your exact actual waste ratio? Too often people assume it is correct and honestly it rarely is. If you don't have the proper waste ratio a membrane doesn't last long.
Is your TDS meter accurate? Do you triple rinse it in RO/DI or distilled water after each use and put it away clean and capped?

Yes, I test my tds Ro water from output membrane and it was 85_87 ppm.
Also my Ro system pre filter is:
Stage 1: 5 micron sediment filter.
Stage 2: 1 micron cto activated carbon filter.
Stage 3 : activated carbon bolck.
Stage 4 : Filmtech dow memberane
Stage 5 : Post carbon that connect to outpost Ro pressure tank.
Stage 6 : Mineral filter.
I connect union tee after memberane output one for my di cartridges for my saltwater tank and other for drinking water.
Also my wastewater ro system flow is 400.
Unfortunately I don't know that should rise my tds meter with ro di or distilled water.

 

[AZDesertRat]

First thing is get a gallon jug of distilled water at the grocery and wash yourself a clear glass drinking water glass in very hot water by hand so it has no dishwasher soap residues or wate rspotting agents to throw TDS readings off. Pour some distilled water in the glass and stick the meter in it an see what it reads, f it is dirty it will not read 0 so you may need to soak the meter and swish it around for a few glasses of water to get the probes inside the meter clean. Once you think the meter is accurate start all over, draw a glass of RO/DI, insert the meter, let it stabilize and write it down. Triple rinse the glass and the meter in the distilled water then take a sample of water directly from the RO membrane once the system has been running 5-10 minutes or longer, before the DI or any fittings. Again insert the meter. let it stabilize and write the reading down. Triple rinse the meter and glass then take a sample of the RO/DI water following tbe same procedures above.

I see a couple of potential issues, one is you are using the system for both drinking water and RO/DI. In order to do this successfully you need to isolate the drinking water from the DI filter with a check valve. Since you say you have a post RO carbon taste and odor filter and a "mineral" filter I assume you have a pressurized drinking water tank?
Follow the diagram here and install a check valve between the pressure tank and the DI filter so the DI does not suffer the effects of TDS creep.
http://spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

Measure your exact waste ratio using a measing cup and clock or watch. Never assume anything. First measure the waste flow for exactly one minute and write the amount down either in mL or ounces then do exactly the same for one minute on the RO treated water. If you are hooked to a pressure tank, disconnect it so you are measuring what the RO membrane does and not what a pressure tank does. Most fixed flow restrictors are ballpark close at best, I will not use one myself as everyones conditions are different and there is no one size fits all if you expect a RO membrane to last and perform well. I much prefer a capillary tube flow restrictor you the end user trim and adjust for your exact water conditions.