Tips for zero TDS water

[AZDesertRat]

Did you also replace the SilicaBuster DI cartridge? It should last as long as 3 MaxCap cartridges before needing replacement as long as you don't let the MaxCap get too far exhausted before replacing it. Once the MaxCap goes it can quickly take the SilicBuster out too if you don't catch it in time. Happened to me once in the early years when I wasn't paying attention.

 

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Thought I revisit this one. It's been about a month. And while the system as a whole seems to be functioning better I can't keep the post di at zero. I bounce around 0.1-0.3. I have been reading more about any Tds in di potentially being a problem so I thought I'd get your input on my readings. To me zero is zero so getting any measurable Tds after di tells me there is still something that could be tweaked.


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[AZDesertRat]

What are you measuring the TDS with and how are you doing the tests?
My suggestion is a good handheld TDS meter such as the HM Digital COM-100 and a nice squeakly clean, clear glass, drinking water glass washed by hand in extremely hot water so it has no water spots or dishwasher anti spotting agents or detergents on it.

Inline TDS meters and most handhelds with the exception of the COM-100 read in whole numbers so what many take to be a decimal point is actually an indicator the meter is on, its really 1, 5, 100 etc and not 0.1,, 0.5 or 10.0 etc. The COM-100 does read down to tenths of a ppm TDS so does have a decimal point.

Using the clean glass, draw a sample of tap water and insert the handheld until the reading stabilizes. Record the reading then triple rinse the glass and meter in RO/DI or distilled water if the DI resin is in question then draw a sample from the RO membrane only before the DI filter. You may need to disconnect the line from the membrane housing to the DI at the DI end or remove the DI cartridge to do this test. I installed a tee and ball valve between my RO and DI so I can draw a sample of RO only at any time plus have a place now to fill containers with RO only for pet watering etc. Stick the meter in the glass and again let the reading stabilize and record the number and do another triple rinse of the meter and glass with RO/DI or distilled water.
Finally draw a sample of RO/DI after the system has been running a couple minutes and do the final TDS test, record the reading and do the final triple rinse so the meter and glass are squeaky clean for next time. If you have a MaxCap dual DI system you would need to test the MaxCap DI TDS first, again I installed a tee and ball valve here, triple rinse then test the final RO/DI or SilicaBuster DI and do a final triple rinse. I cap the meter and invert the glass so it keeps dust and salt spray out.

The RO only should be 98% lower TDS than the tap water and the goal is 0 TDS out of both DI cartridges. Anything out of the ordinary is an indication of a problem somehwhere. it could be a bad membrane, bad membrane housing, exhausted DI resin, high CO2 in your water etc. CO2 is often overlooked but greatly shortens DI life unless you degass the CO2 from the water.

If you have a MaxCap system and the two dual inline TDS meters, what does each In and OUT read left to right?

 

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I am using a com 100. On my phone now so as soon as I get behind my computer ill answer thoroughly.

Thanks for your lighting fast response. Really appreciate it


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[Battlecorals Verified Sponsor]

Ok back home

My method for measuring is pretty much what you suggested. I have a clean glass that I rinse thoroughly with the DI water many times before and during the test. I have teed off lines at just about every stage that I use to check with the com.


At about 52 degrees

tap is 450-550
RO after at least one hour between 5-8 tds
DI 0.1-.03

I have four total inlines on the maxcap they pretty consistently read
pre max 2-5
max 1 out 0
max 2 out 0
post SB 0


I had been using a booster pump but it changed my output ratio to 3:1 from 4:1 so I have been leaving it off. Still getting 4:1 pretty consistently.

I am running two maxcaps before one spectrapure SB cartridge


I can hit 0.0 on the com out of the first maxcap when I am flushing it but by the time the water gets to the final stage it seems to pick up a point or three.

I do understand that even the air can raise the tds as I have seen my zero turn to 0.1 within a few seconds of reading zero but after long running filter times I am still not steadily hitting zero.

I guess my ultimate question is, should my water read 0.0 steadily or are the small tds readings negligible or possible tolerable margins for the com?


I have tested after the filter has been running for nearly 24 hours and many times in between. Sometimes i'll see 0.0 but it usually reads 0.1 at least.

If I have left anything out please let me know and i'll do the best I can.


Thanks again

 

[AZDesertRat]

Since you are seeing fractions of a ppm TDS and not whole numbers I wouldn't be too concerned, it may just be within the level of accuracy of the meter. When you start seeing whole numbers is when you need to start looking at replacement time.

I'm not sure about the two MaxCap cartridges in front of the SilicaBuster. I do know the MaxCap changes the pH of the water and is one of the good things about how it works so well in extending the life of the downstream DI cartridge but two may not be good.
I would contact Spectrapure and talk with their Tech people who should be able to help you out. I would also check on a different flow restrictor you can trim to get the 4:1 waste ratio using the booster pump, I know when I boost my pressure up to 90-100 psi my rejection rate improves and the DI life goes up. The folks at Spectrapure love a challenge and I'll bet they can do something for you. I have volunteered as a Guinea Pig a couple of times when they are Beta testing something new or uncommon.

 

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That is a great idea. I'd love to bounce a few other questions off them as well. Ill have to give them a call. As for the maxcaps. I seem to recall in the manual something about the more cartridges you run is exponential in preserving the final stage. Maybe I should double check that though.

Thanks again for all your help


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[Battlecorals Verified Sponsor]

No I was wrong. I just looked at the manual again and they say you can run three maxes before you exhaust the final di.

They do not mention running more than one actual cartridge. I definitely read that wrong.

Ill ask them about that as well




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