High TDS reading on new filters

[Scribe]

So I just replaced my filters on my Ro/Di unit with the same ones I had from spectra pure. I ran the unit for about 2 hours after installing them, and I'm getting a reading of 10 on my TDS meter. Any ideas? I repllaced them, because I was getting a reading of 4 before. Wish I had kept them now. Sorry if this is the wrong place for this post.

 

[ReelRednekReefer]

What is your source water tds?

Is it 10ppm tads after RO filter or after RO and DI?

 

[AZDesertRat]

Exactly which filters did you replace and with what? Did you disinfect the system while it was down as recommended? Did you flush each filter in sequence before installing the next? What is your tap water TDS, RO only TDS and final RO/DI TDS now and what was it before?
What is your water pressure, water temperature and exact measured waste ratio?

 

[Scribe]

I have to check my source and RO only tds.

AZ Desert Rat - I replaced all filters in the unit with these two packages - FK-CSPDI-HC and MEM SP0090. I did not disinfect the system, or flush each filter. I replaced just like I have in the past. My pressure is about 46.

 

[AZDesertRat]

You should always check all three TDS readings, one does not do you any good without the other two.
Looks like we went through this same thing a year ago
https://www.reef2reef.com/forums/eq...o-de-ionization-replacement-cartridges-2.html
and I asked the very same questions and made the exact same recommendations then.
Why are you replacing the RO membrane, it should last 5-7 years or longer if you keep up with the sediment and carbon replacements and do an annual disinfection.

Here is one of my older posts on the proper way to disinfect a system and replace the filters:

The proper way to replace filters and membranes is as follows:

Remove all the old filters and membrane, rinse everything is warm soapy water and rinse well, reassemble all the empty housings placing two tablespoons of regular unscented bleach in the sediment filter housing then slowly turn the water on and let the housings all fill up until water starts to exit the lines. Shut it off and let it disinfect for a few minutes then open the supply again and flush the chlorinated water through until all scent of bleach is gone.
Install the new RO membrane and disconnect the line leading up from the carbon block to the RO membrane at the membrane housing end and stick this line in a bucket or the sink. Install ONLY the sediment filter and open the water supply for a couple minutes, sending the water down the drain or in the bucket to rinse away any glues or binders used in the filter making process. Next, shut the water off and install the carbon block, repeating the flushing process for a couple minutes to flush out and carbon dust or fines so they don't contaimnate or foul the RO membrane. Repeat if you have the old style dual carbons which I do not recommend.

Now, shut the water off and reconnect the 1/4" line from the carbon to the RO and turn the water back on. it will be much slower now since it is going through the membrane but make 3-5 gallons or RO water sending it to the drain to flush any antimicrobial treatments the membrane may have on it to the drain and not foul and shorten the life of the DI resin. at this point you can monitor the RO TDS and watch it falling to a final low point after the membrane becomes saturated and cleaned. I also pick the whole system up in my hands and rotate it all around to release any trapped air in the housings.

Finally install the new DI cartridge or resin and run 3 or 4 cartridge volumes of RO/DI to waste, again your TDS meter will help here and you should end up at 0 TDS.

By not following these steps you contaminate and shorten the life of whatever is downstream of the new replacement in line.

If you are not replacing the RO membrane which is usually the case may double sure you disconnect the RO housing from the carbon during the disinfection process and flushing so you do not get any bleach near the RO membrane which can damage it. I alwaysl disinfect and flush every time I replace sediment and carbon filters to be safe and it only takes a couple minutes extra time.​

 

[Scribe]

I don't know how I missed this part of the post last year, but thank you so much for all the info. I have pulled the filters and membranes and rinsed in soapy warm water. I reassembled the empty housing, and have bleach sitting in there now. I got the rest of the TDS readings too.

Tap water = 411
RO = 7
RO/DI = 11

 

[AZDesertRat]

At 46 psi your pressure is marginal but will work, just not as efficient as it would at 60+ psi.
Have you measured the waste ratio to make sure you are at or close to 4:1 waste to treated?
How much water have you run through the new DI? Normally the DI will rinse up and be 0 TDS after only a few bed volumes or quarts of treated water. How are you taking the TDS readings and with what? I like to use a squeaky clean clear glass drinking water glass washed by hand in very hot water so it has no dishwasher soap residues or antispotting agents to interfere with the TDS readings. I also use a good HM Digital handheld TDS meter with ATC so it is accurate.
Draw a glass or tap water, insert the handheld meter and let the reading stabilize before recording the reading. Next triple rinse the glass and meter in RO/DI or distilled water then draw a glass of RO only water and again insert the meter and let the reading stabilize before writing it down. Triple rinse the meter and glass in RO/DI or distilled water. Finally let the glass fill with RO/DI directly from the unit, insert the meter, let it stabilize, write it down and do a final triple rinse of the meter and galss before capping the meter and turning the glass upside down so it stays clean for next use. If you suspect your DI may be bad buy a jug of distilled water for the rinsing and to check to see if the meter reads 0 TDS with distilled for a reality check.

A tap TDS of 411 and RO only of 7 means your membrane is 98.2% rejection rate. This will probably improve a little with time and would really improve with higher pressure. You don't have a pressure regulator on your incoming water you could adjust do you?

 

[Scribe]

Ok. I'll go try the testing again once I'm clear of the bleach smell. Still running it out. The township we live in requires a pressure regulator on our water coming in. I'll have to see if I can adjust. The meter I'm using to test is a HM digital TDS-3 hand held.

 

[Scribe]

Sorry I ran at least 20 gallons through the filter before this, and was still getting the 10-11. I have not measured to see about the 4:1 I will put that on the list as well.

 

[pickupman66]

Did you replace your DI resin too? this seems odd to me that it is higher after the DI than it did the straight RO. in looking at your #'s the 411 to 7 is pretty darn good for the Membrane.

 

[Scribe]

Yeah, I replaced everything. I just flushed the season and sterilized, now I'm getting 97 with just the RO in. Going to let it run for a bit and see what happens.

 

[Scribe]

Sorry for the delay, after the cleaning here are my numbers.

Tap 450
Ro 6
Ro/di 16

Also it's seems like waste to filtered water is about 3:1

Should I assume something is wrong with the DI Resin. Seems strange to get a higher number with it, then without it.

 

[AZDesertRat]

Your RO membrane is very good, it is operating at 98.6% rejection rate so very efficient. Your DI is shot though. A 3:1 waste ratio is a little low for 450 TDS tap water unless it is softened water. Are you using a brand new vacuum sealed and properly stored DI cartridge or is it bulk resin that was previously opened? Resin has a relatively short shelf life and must be properly stored or it loses its electrical properties quickly.

 

[Scribe]

The source water is softened, and everything was stored in the fridge. The Di membrane was never opened. Before if installed it.

 

[AZDesertRat]

What DI resin is it and how much water did you run through it before testing. Are you using a handheld or inline meter? If it is an inline try swapping the probes to see if they agree or are at least close.

 

[Scribe]

I think this is the model FK-CSPDI-HC. I would have to guess at this point maybe 50 gallons have run through it. The TDS Meter is handheld.

 

[ReefCartel]

Hey just wondering. On the triple TDS meter when it starts reading numbers on Meter #1 and it starts counting down. Is that time to replace only the 1st Sediment filter? Should i dump that water I stored?

 

[AZDesertRat]

Not sure how you have your meter hooked up but normally it would be tap water on the first probe, RO only on the second and DI on the third with a three probe meter and a RO/DI with a single DI. Dual TDS meters are usually post RO and final RO/DI so you miss out on the tap TDS which is a necessary measurement to calculate the rejection rate.
When you say counting down though it soulds like the probe is after the RO and is reading the results of TDS creep which flushes itself out as the system runs. Need to know where the probe is located to know for sure.

 

[Scribe]

So I just replaced my DI resin today and got a reading of zero. This makes me 99% sure it was a bad DI Resin. Hopefully they will replace it, or refund me for it, else I'll be shopping elsewhere. Thanks for everyone's help, especially you AzDesertRat. Your knowledge is greatly appreciated.

 

[AZDesertRat]

One thing I am careful with is DI. I will not buy DI from another vendor such as Premium Aquatics or Maine Depot even though they sell Spectrapure products unless it is drop shipped directly from Spectrapure and has not been sitting on a shelf somewhere. I also do not buy DI cartridges or resin ahead of time since it has a shelf life and exhausts quickly if not stored properly or installed right away.

Hopefully they take care of you, they are pretty good when it comes to customer satisfaction.