What is ZERO TDS? Is it real??

[SpectraPure]

I thought I would comment on the common misnomer "ZERO TDS". Persons stating ZERO TDS I assume are referring to Zero Indicated TDS. What's the difference you ask? Well, quite a bit when you are really talking about ultrapure water. Ultrapure water is about 18.2 mohms or about 0.05 microseimens. Most Reefers are after such ultrapure water in our experience. Thus, if there were such a thing as "ZERO TDS", it might be more appropriately measured around 0.05 micro siemens. Unfortunately, most (not all) inexpensive TDS meters can resolve at best about 5 micro seimens. That is several decades less sensitivity than required to be stating so called "ZERO TDS".

While 5 micro siemens conductivity (at an affordable price and rugged instrument easily operated and maintained) is very reasonable for for break-through detection to signal cartridge replacement required, it is clearly not sufficient to measure or crow about having “ZERO TDS� . Thus, postings where one has "measured" a system or component performance and state they have "ZERO TDS" should be careful to quantify the accuracy of the instrument they are using to make such a claim. Hopefully this will shed some light on... zero is not always zero.

[crescent1]

uhm,what.

[GuySmilie]

Originally posted by SpectraPure
I thought I would comment on the common misnomer "ZERO TDS". Persons stating ZERO TDS I assume are referring to Zero Indicated TDS. What's the difference you ask? Well, quite a bit when you are really talking about ultrapure water. Ultrapure water is about 18.2 mohms or about 0.05 microseimens. Most Reefers are after such ultrapure water in our experience. Thus, if there were such a thing as "ZERO TDS", it might be more appropriately measured around 0.05 micro siemens. Unfortunately, most (not all) inexpensive TDS meters can resolve at best about 5 micro seimens. That is several decades less sensitivity than required to be stating so called "ZERO TDS".

While 5 micro siemens conductivity (at an affordable price and rugged instrument easily operated and maintained) is very reasonable for for break-through detection to signal cartridge replacement required, it is clearly not sufficient to measure or crow about having �ZERO TDS� . Thus, postings where one has "measured" a system or component performance and state they have "ZERO TDS" should be careful to quantify the accuracy of the instrument they are using to make such a claim. Hopefully this will shed some light on... zero is not always zero.

Very well stated SpectraPure. This is indeed a common misconception in the marine hobby.
By the way which of the "(not all) inexpensive TDS meters" do you suggest that can resolve to the 5 uS level?
Guy

[SpectraPure]

The COM-100 is by far the best-resolving meter we know of for less than $50.

Scott
SpectraPure, Inc.

[mr. pluto]

hello scott, i have a entry level meter, i measure 0 on my meter
& 37ppm on my waste water, at what point do you
change filters? btw i use your filters.

[SpectraPure]

Zero is good. I don't have enough information to say anything else.

Scott
SpectraPure, Inc.

[mr. pluto]

i can check data before di, which is 2 ppm or after =0
or waste=37 or tap which is 24.
(prefilter, .05 carbon block , r/o di= di sp10, arc1 10.
i must change my filters way to early! 6 months for all
but r/o. since i know i do not have a quality meter. i wanted to know the ballpark # which one would do a change out.
meter =TDS METER 4TM

thanks

[SpectraPure]

If you don't trust your meter, how can I tell if you have true numbers?

If your tap water is really only 24 TDS, you should not be having any trouble with your system.

What do you mean by " r/o di= di sp10, arc1 10. " ?

Are those somebody else's DI carts?

Scott
SpectraPure, Inc.

[mr. pluto]

not that i don't trust it. this is my first exposure to using the meters thats all. those are your di # di-ar-10,di-sp-10.
i have been flying blind so to speak for 5 yrs. without the tool.
i'm not complaining.

[SpectraPure]

1. We don't sell a cartridge labeled, "di-sp-10". Some distributors say they are selling a SpectraPure DI cart and label it as something slightly different, such as "di-SP-10". This lets them get away with SUBSTITUTING whatever they can buy the cheapest for a real SPECTRAPURE product. From whom did you purchase these carts?

2. If you have, in fact, a DI-AR-10, it should only be used following our DI-SF-10 cartridge. Any other combo using the DI-AR-10 won't work effectively. We now recommend our DI-MC-10 followed by our DI-SB-10 for optimum performance.

3. The 4TH is a decent meter. Use it. If you really have only 24 TDS tap water, you should have a long life, so I'm back to suspecting the origin of the di-sp-10 cart and the improper arrangement thereof.

4. I would be very surprised, with 24TDS water, that you have to replace the pre-filters so often. Does the pressure on the membrane drop, indicating that the pre-filter is plugged up?

Scott
SpectraPure, Inc.

[jnarowe]

Originally posted by SpectraPure
The COM-100 is by far the best-resolving meter we know of for less than $50.

Scott
SpectraPure, Inc.

What about in-line meters? Are there any that measure less than 1ppm?

[SpectraPure]

See the bottom of this page:

http://spectrapure.com/St_quality_p7.htm

Scott
SpectraPure, Inc.

[ReefEnabler]

I have a HM TDS3 meter. It reads ~150ppm for my tap water and 0 for my output water.

Does the TDS3 compare to the COM100 for accuracy at low ppm levels?

[SpectraPure]

The COM-100 is the more accurate meter.

Scott
SpectraPure, Inc.

[khoivo1]

helo,,i have a com-100 and i check tds is reading 12,,,is that bad?? what number is accepted??

[SpectraPure]

You need to know the TDS of your tap water, then:

tapTDS - roTDS / tapTDS X 100 = %rejection.

Greater than 96% is accepted.

Scott
SpectraPure, Inc.

[CeeGee]

Is there a TDS meter that allows people who work at spectrapure to answer emails? If so you guys need to invest in one.

[SpectraPure]

I'm sorry, we continue to experience many absences since the holidays due to the flu that is going around. Your email looks like it got buried or went missing in the resulting overload as neither sales person had it flagged. Not an excuse, I just looked into the mail files and noted this to be the case. If you do not receive appropriate response you can email me at my first [email protected] and I will follow up with our folks.
Thanks for your feedback, I will share it with our team in todays sales meeting as an example of a problem that we must not allow to repeat, even if it happens rarely (from our view)
bruce
spectrapure

[Sandberg]

Originally Posted by SpectraPure

The COM-100 is by far the best-resolving meter we know of for less than $50. Scott
SpectraPure, Inc.

Hi Scott. Very important information about 000ppm - that is does NOT exist, especially with the cheaper meters. Do you use a reference professional meter, since you write this about the COM-100 (I have seen you say that the COM-100 is 'incredible accurate' on your site)? If you do, could you please recommend a reference meter?

[SpectraPure]

I'm not in the office today, but I am sure Bruce can find out and let you know.

Scott
SpectraPure, Inc.

[SpectraPure]

Thorton makes a nice line of high quality laboratory instruments.
That said, the COM 100 instrument is an appropriate meter for the application here, that is - RO DI water for aquatic applications. thus, "appropriate" is determined by a number of factors, not least of which is what purity water is suitable for the application.
regarding an "appropriate" instrument, having run an APIMS for years I would not want you to get caught up in using a telescope to see a pelican in your water for your tank. Sure you can detect trace impurities at the ppb level, but is it neccessary to improve the aquatic environment?
In other words, it is our opinion that the COM-100 is a cost effective means of testing your water purity for the aquatic applications followed on this forum.
If you were manufacturing 12 inch slices worth $150,000 or more per slice and part per trillion detection LDL's were critical to the yield of those devices, you could afford to spring the $600k an APIMS used to cost to run diagnostics and monitoring on your DI water.
Hope this helps.
Bruce

[Sandberg]

Bruce: yes, helps a lot. I get the point. I just talked with someone in your office. You are very kind and helpful. I have only been short time in business with RO and DI and I just want to say to you americans: You are lucky to have Spectrapure in your country. As far as I know from Europe, there is absolutely no company, that comes close regarding expertise, knowledge and products.

Unfortunately shipping costs are very high to Europe. I have learned a lot reading here in the forum and also on your site, thanks a lot.

[SpectraPure]

No problem. We are happy to accommodate any questions you might have.
Shane.