I need a TDS meter. What do you recommend?

[DonMD]

I've been searching through previous threads on this subject, but can't seem to come up with a solid recommendation.

I want to measure TDS now that I'm hoping Hans will (eventually, one day) send me the pair I've got on order! Meters range in price from $20 to $150 or so. If you use a TDS meter, what's your recommendation?

Thanks, -Don

[DiscusLoverJeff]

Hey Don,

I use this

http://www.bulkreefsupply.com/tds-3-handheld-tds-meter-hm-digital.html?gclid=CPjd5tXMwLYCFY9DMgodBi8A0Q

and this for the TDS/PH/Temp readings

http://www.amazon.com/Hanna-Instruments-Waterproof-Conductivity-Tester/dp/B002ZG8L58/ref=sr_1_14?ie=UTF8&qid=1365614091&sr=8-14&keywords=tds+meter

The Hanna is good but over priced in my opinion because the ph readings are all over the place after a month or so.

If you can get it under $100.00 its not bad.

[Chad Hughes]

Don,

I find that conductivity meters are better and I recommend and own an EC-3 by HM Digital. You can get them on Ebay for $22 with free shipping.

If you really want a TDS meter HM also makes an TDS-EZ meter. I also own one of these but rarely use it. It can also be found on Ebay for $15.88 with free shipping.

Hope that helps!

[Skip]

i got mine from EBAY.. pretty cheap.. US SELLER

[GlennR]

I have an Oakton that I really like. Had a Hanna, but it died after 2-3 years.

Btw, I wouldn't recommend a TDS/pH combo unit because when it breaks you've lost 2 meters at the same time!

[DonMD]

Don,

I find that conductivity meters are better and I recommend and own an EC-3 by HM Digital. You can get them on Ebay for $22 with free shipping.

If you really want a TDS meter HM also makes an TDS-EZ meter. I also own one of these but rarely use it. It can also be found on Ebay for $15.88 with free shipping.

Hope that helps!

Thanks, Chad. Can you explain your preference for measuring conductivity over TDS? It's all a mystery to me! LOL.

[DonMD]

Hey Don,

I use this

http://www.bulkreefsupply.com/tds-3-handheld-tds-meter-hm-digital.html?gclid=CPjd5tXMwLYCFY9DMgodBi8A0Q

and this for the TDS/PH/Temp readings

http://www.amazon.com/Hanna-Instruments-Waterproof-Conductivity-Tester/dp/B002ZG8L58/ref=sr_1_14?ie=UTF8&qid=1365614091&sr=8-14&keywords=tds+meter

The Hanna is good but over priced in my opinion because the ph readings are all over the place after a month or so.

If you can get it under $100.00 its not bad.


I have an Oakton that I really like. Had a Hanna, but it died after 2-3 years.

Btw, I wouldn't recommend a TDS/pH combo unit because when it breaks you've lost 2 meters at the same time!

Thanks, I'll check them out!

[strawberryblonde]

I just bought an HM TDS4 a few days ago on Amazon for $20 with free shipping. It won't arrive till tomorrow, so I'll update the thread with my results once I use it a couple of times.

[Chad Hughes]

Don,

My straight forward answer?? :D

TDS is measured using a Conductivity meter and is then factored within the meter. Depending on the conversion factor setting of the meter, you never quite know what reading you're getting. The Conductivity reading is converted using a mathematical formula based on what is known as 442, which is a mixture of sodium sulfate (40%), sodium bicarbonate (40%) and sodium chloride (20%). The 442 mixture is designed to mimic the ions often present in natural fresh water systems.

Conductivity is what it is, no conversion. Here's some examples of salts at 0.01mol/l solution and their conversion factors... (notice how the conversion factors change)

NaCl TDS 584 µS 1156 conversion factor 0.51
CaCl2 TDS 1110 µS 2310 conversion factor 0.48
NaHCO3 TDS 840 µS 865 conversion factor 0.97

So, depending on your solution, and every tap water sources is different, your TDS conversion factor could screw you up. :)

Bottom line, I like to know my conductivity.


Thanks, Chad. Can you explain your preference for measuring conductivity over TDS? It's all a mystery to me! LOL.

[the20tonknuckler]

Great detailed answer Chad. I'm always learning something from you. Btw I got my tds meter off ebay for 15 bucks.

[a volar]

Don,

My straight forward answer?? :D

TDS is measured using a Conductivity meter and is then factored within the meter. Depending on the conversion factor setting of the meter, you never quite know what reading you're getting. The Conductivity reading is converted using a mathematical formula based on what is known as 442, which is a mixture of sodium sulfate (40%), sodium bicarbonate (40%) and sodium chloride (20%). The 442 mixture is designed to mimic the ions often present in natural fresh water systems.

Conductivity is what it is, no conversion. Here's some examples of salts at 0.01mol/l solution and their conversion factors... (notice how the conversion factors change)

NaCl TDS 584 µS 1156 conversion factor 0.51
CaCl2 TDS 1110 µS 2310 conversion factor 0.48
NaHCO3 TDS 840 µS 865 conversion factor 0.97

So, depending on your solution, and every tap water sources is different, your TDS conversion factor could screw you up. :)

Bottom line, I like to know my conductivity.

Very straight forward answer Chad :)

[Chad Hughes]

Always glad to help! Sounds like you got a good deal. ;)


Great detailed answer Chad. I'm always learning something from you. Btw I got my tds meter off ebay for 15 bucks.

That's about as simple as I could explain it. :D


Very straight forward answer Chad :)

[Buckeye Field Supply]

Let me say right off the bat that we've been an HM Digital distributor for years, so we may be a little biased.

The TDS meters do first measure conductivity, and then they mathematically translate that into TDS. All of the HM meters use the NaCl factor rather than the 442.

The temperature of the fluid affects TDS, so you'll want a meter with ATC (automatic temperature compensation). The very very basic meter mentioned above, the TDS-EZ, is at the very low end of the cost spectrum, and it does not have ATC. The TDS3 and TDS4 mentioned above DO have ATC. At the other end of the HM Digital spectrum is the COM-100. It is waterproof (you can drop it in a bucket of water w/o damage), you can choose from three factors used to convert EC to TDS, and it is more precise than the other meters.

One last word: Be VERY careful buying TDS meters on ebay. Ebay is LOADED with counterfeit units. Most of them seem to come out of Asia. For example: http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=160998724960&ssPageName=ADME:X:RTQ:US:1123
I know HM Digital products are heavily counterfeited - so I assume that's also the case for other manufacturers - but I don't know that for certain. For the average person I think it would be very difficult to tell the difference when you see them on ebay.

Russ

[nc0gnet0]

Best thing to do is buy yourself a small bottle of calibration solution and periodically check the meter. IMO consistancy is a much bigger factor than pinpoint accuracy.

[Chad Hughes]

Russ,

GREAT info! Thanks brother!


Let me say right off the bat that we've been an HM Digital distributor for years, so we may be a little biased.

The TDS meters do first measure conductivity, and then they mathematically translate that into TDS. All of the HM meters use the NaCl factor rather than the 442.

The temperature of the fluid affects TDS, so you'll want a meter with ATC (automatic temperature compensation). The very very basic meter mentioned above, the TDS-EZ, is at the very low end of the cost spectrum, and it does not have ATC. The TDS3 and TDS4 mentioned above DO have ATC. At the other end of the HM Digital spectrum is the COM-100. It is waterproof (you can drop it in a bucket of water w/o damage), you can choose from three factors used to convert EC to TDS, and it is more precise than the other meters.

One last word: Be VERY careful buying TDS meters on ebay. Ebay is LOADED with counterfeit units. Most of them seem to come out of Asia. For example: http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=160998724960&ssPageName=ADME:X:RTQ:US:1123
I know HM Digital products are heavily counterfeited - so I assume that's also the case for other manufacturers - but I don't know that for certain. For the average person I think it would be very difficult to tell the difference when you see them on ebay.

Russ

[DonMD]

This is all great information from everyone. Thanks!

[seanyuki]

I am also using the HM TDS digital meter.......what kind of solution to calibrate/ and how often ?

[Buckeye Field Supply]

There are various brands of TDS calibration fluid available at various TDS levels. Get one that is nearest what you expect to be measuring. So if you are measuring 0 ppm DI water, don't calibrate with a 1382 ppm fluid for example. Some meters require a specific ppm calibration fluid, while others can be calibrated to whatever fluid you use.
http://i224.photobucket.com/albums/dd293/BuckeyeFS/Meters%20and%20Controllers/calibration_bottles.jpg (http://s224.photobucket.com/user/BuckeyeFS/media/Meters%20and%20Controllers/calibration_bottles.jpg.html)

Russ

[Carolina discus]

Russ is the man for your RO and meter needs, excellent products and the support to help you along the way.....all members should try to support him more...

[DonMD]

There are various brands of TDS calibration fluid available at various TDS levels. Get one that is nearest what you expect to be measuring. So if you are measuring 0 ppm DI water, don't calibrate with a 1382 ppm fluid for example. Some meters require a specific ppm calibration fluid, while others can be calibrated to whatever fluid you use.

Russ

Thanks, Russ. I was just curious about my city water supply, I don't have an RO unit. I've had fish breed successfully for me in the past. After setting up my system again last year, I brought in 9 fish from Hans. I've had a pair spawn several times, but the eggs never made it to wiggler ~ as far as I can tell I had two females together. But on the off chance that my water could have been the issue I thought I'd check the TDS. So in this situation, which calibration solution would be best, the 1,000 ppm, or the 342? -Don

[Buckeye Field Supply]

After looking at some of the water quality reports for Fairfax, and assuming you'll be testing primarily the TDS in tap water, go for the 342 ppm.

Russ

[DonMD]

After looking at some of the water quality reports for Fairfax, and assuming you'll be testing primarily the TDS in tap water, go for the 342 ppm.

Russ

I appreciate that. Thanks.