RO/DI question

[yzfr6]

I purchased a used Kent RO/DI unit rated at 100 gpd. I purchased a TDS meter to test the system. The RO water currently read at .35 and my normal tap water is at 1.70. so it appears to be working. I just thought I was supposed to have it at 0. Any ideas? the guy that sold me the unit said the filters were only a couple of months old.

 

[der_wille_zur_macht]

Are you literally measuring the RO water (as per your wording) or are you measuring the unit's effluent (i.e. after the RO AND the DI stages)?

What units are you reporting those values in?

 

[kraze3]

Have you wasted the first 5 gallons or so to let it break in?

 

[yzfr6]

I am sticking the tds meter in the RO/DI water after the final stages. so its the exact water I am putting in my aquarium.

 

[yzfr6]

yeah, this is about 40 gallons after I got the unit.

 

[misiek]

get some Distilled water and check TDS it should be 0ppm if is not you have to calibrate your TDS meter

 

[IslandCrow]

I've never had distilled water read 0, so I don't think that's a very good test. RO/DI is generally going to be more pure than any distilled water you buy (unless you're getting it from a lab). .35 may indeed just be a calibration error, but your numbers just don't sound right. I've heard of people having really low TDS tap water, but 1.70? That sounds very unlikely to me. What kind of TDS meter do you have, and what units is it measuring in?

 

[yzfr6]

<a href=showthread.php?s=&postid=14822403#post14822403 target=_blank>Originally posted</a> by misiek
get some Distilled water and check TDS it should be 0ppm if is not you have to calibrate your TDS meter

Okay, I can check it that way but it was calibrated at the factory. If this is correct is .35 acceptable? It says on the back of it that anything from 0-50 is RO/DI water..

 

[der_wille_zur_macht]

Can you confirm the units your device is measuring in? More typical values might be 170 for tap water, not 1.70.

 

[stingythingy45]

<a href=showthread.php?s=&postid=14822576#post14822576 target=_blank>Originally posted</a> by der_wille_zur_macht
Can you confirm the units your device is measuring in? More typical values might be 170 for tap water, not 1.70.

Really what's up with the"."?
Typical reading are in whole numbers.
I'm guessing his ro water is 35 and tap water is 170 ppm.

 

[daniel_a_blake]

my unit took a lot more than 5 gal to break in before the readings went to 0, but 40 gal should be plenty. I also agree on the readings should 170+ for tap water and less than 1 for filtered. Prefereably 0 for filtered. What kind of unit are you using?

 

[yzfr6]

sorry, you are correct it is 35 ppm and 170 for tap water. I got it off of ebay. Below is the stats:

Water Quality TDS Tester

TDS-EZ



These Meters Are
BRAND NEW

RETAIL PRICE $29.00

We are selling way below retail!!

ONLY $15.95 EACH


FEATURES

* Economy model that is ideal for end-users.
* Highly efficient and accurate due to its advanced microprocessor technology.
* Hold Function: saves measurements for convenient reading and recording.
* Auto-off function: the meter shuts off automatically after 10 minutes of non-use to conserve batteries.
* Measurement Range: 0-9990 ppm. From 0-999 ppm, the resolution is in increments of 1ppm. From 1000 to 9990 ppm, the resolution is in increments of 10ppm, indicated by a blinking 'x10' image.
* Display: large and easy-to-read LCD screen.
* Factory Calibrated: our meters are calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver.
* Fun, translucent blue housing that's very strong and durable.
* Includes a TDS chart sticker on the back of the meter that explains TDS values.
* Comes in a retail-oriented package.

Calibration Solutions (sold separately) are available in our Ebay Store
CLICK HERE TO GO TO OUR EBAY STORE
SPECIFICATIONS

* TDS Range: 0 - 9990 ppm (mg/L)
* Resolution: 1 ppm (0-999 ppm); 10 ppm (1000-9990 ppm)
* Accuracy: +/- 3%
* Power source: 2 x 1.5V button cell batteries (included)
* Battery life: Approx. 1000 hours of usage
* Dimensions: 15.5 x 3.1 x 2.3cm (6.1 x 1.25 x 1 inches)
* Meter weight: 56.7g (2 oz)
* Weight with package: 76.5g (2.7 oz)

 

[yzfr6]

Its is a Kent RO/DI 100 GPD unit..

 

[becact]

Step one is to verify the TDS meter. See if there is anyone near you with an accurate one so you can test yours against theirs. Or, test yours in a standardized solution (NaCl).

If the meter is reading correctly, then it sounds like it's filter replacement time. You can try flushing the membranes first, though, if your unit has a flush valve.

 

[yzfr6]

<a href=showthread.php?s=&postid=14823491#post14823491 target=_blank>Originally posted</a> by becact
Step one is to verify the TDS meter. See if there is anyone near you with an accurate one so you can test yours against theirs. Or, test yours in a standardized solution (NaCl).

If the meter is reading correctly, then it sounds like it's filter replacement time. You can try flushing the membranes first, though, if your unit has a flush valve.

It does not have a flush valve, so where is a good place to purchase new filters? I have never replaced one before. Do I also need to replace the membrane?

 

[stingythingy45]

What kind of filter is it?
Airwaterice.com sells a nice replacement kit.
I just did a 4 filter change in my ro/di.They recommend changing the carbon,and sediment every year and the ro membrane every 2 years.
I would say that your unit is due.
My drinking water from the unit is 13 tds and the ro/di is 0.

 

[stingythingy45]

Maybe this will work?
But really all standard size filters are interchangeable.

http://www.marinedepot.com/ps_ViewI...osis-Saltwater_Aquarium_Supplies~vendor~.html

If you can swing the extra cost get the inline dual TDS meter at the bottom of the page.I just got one with my last puchase and it's a nice thing to have.