The Questions

Question 1: I'm looking at Total Dissolved Solids portable (preferably "pocket") meters and wondered what experience folks have had with them as far as durability, cost, accuracy, etc.

Question 2: Does anyone have any experience and advise on which TDS meters are the best ones to use, considering both accuracy/precision and ease of calibration/use?

Question 1

Date: Wed, 16 Mar 2005 13:18:00 -0600
From: Steven Witmer <switmer@ci.johnston.ia.us>
Subject: [volmonitor] Total Dissolved Solids - meters

Hello all,

I'm looking at Total Dissolved Solids portable (preferably "pocket") meters and wondered what experience folks have had with them as far as durability, cost, accuracy, etc. I'm looking for something that is inexpensive (of course) but yet accurate enough to be worthwhile and durable enough for field use. I've seen price ranges from as low as around $20, while others are more like ten times that and everything in between. I'd hate to go cheap and end up with something that won't serve it's purpose or last more than a week, but on the other hand I'd rather not spend a lot of money if there is something cheaper that will do just about as well.

Feel free to respond to the list - I'm sure others out there would be interested as well. If there are any comments on field meters generally regardless of parameter, I'd be happy to see those, too.

Thanks,

Steven Witmer

Responses

Date: Thu, 17 Mar 2005 11:03:38 -0500
From: Ginger North <ginger@dnsashland.org>
Subject: RE: [volmonitor] Total Dissolved Solids - meters

Steve - We have used several different conductivity meters over the years & the ones we are using now are easy to use, reliable, not as accurate as some but sturdy in field conditions & wide temperature ranges. They are Oakton brand & come in Total Dissolved Solids readout as well as conductivity & for an extra $20 you can get temperature readout as well. The ones we use are about $55 & handheld "pocket" meters. We have been only using them for the past 2 years so I am not sure about their lifespan as yet. Some of the meters we have used in the past only have a limited lifespan - 3 or 4 years. At $55 we can afford to replace them after a few years however. They only read in increments of 10uS for the low range (0-1990uS) which is plenty sensitive for our purposes. Oakton ECTestr Low is model we use. The TDS model is called TDStestr Low (0-1990ppm)resolution is 10ppm & TDSTestr High (0-10ppt).
Ginger North
Stream Watch Coordinator
Delaware Nature Society
302-239-2334x100
Fax 302-239-2473
ginger@dnsashland.org
www.delawarenaturesociety.org

Date: Tue, 22 Mar 2005 13:51:07 -0600
From: Steven Witmer <switmer@ci.johnston.ia.us>
Subject: [volmonitor] TDS meter response

I thought I'd share the results of my query to the group for TDS portable meters. I got several responses on and off the list, and all of them pointed me toward Oakton low-range models, and most recommended the waterproof models especially. Cost on them (based on the responses and from online browsing I've done) runs around $60 or so.

My thanks to everyone who shared their comments!

Steven Witmer

Question 2

On Wed, Feb 10, 2010 at 11:16 AM, Wilderman, Candie <wilderma@dickinson.edu> wrote:

We are currently developing a protocol for volunteer monitors to be watchdogs for impact from Marcellus shale gas development activities in PA. As part of that protocol, we would like to measure Total Dissolved Solids, using one of the many small TDS meters (which actually measure conductivity) that are now on the market.

Does anyone have any experience and advise on which ones are the best ones to use, considering both accuracy/precision and ease of calibration/use? We would like to spend less than $100 per meter. What would be the most important features to consider in making this choice?

Any advise would be greatly appreciated! If folks would like, I'd be happy to compile responses and post.

Candie Wilderman
Founder and Science Director
Alliance for Aquatic Resource Monitoring (ALLARM)
Dickinson College
Carlisle, PA 17011
717.245.1573

Responses

On Wed, Feb 10, 2010 at 12:36 PM, Chris Riggert <Chris.Riggert@mdc.mo.gov> wrote:

Hi Candie,

We have used a couple of TDS/conductivity pens over the years with the MO Stream Team's VWQM. The first pen was a 'TDS' pen, but as you accurately surmised, it was really measuring conductivity and doing a mathematical calculation to provide the reading. About 10 years ago we switched to the Pocket Pal Conductivity Tester from Hach (# 2686601, $67.89). When these pens worked, they worked very well, and were relatively inexpensive. However:
- they were a bear to calibrate because of the placement of the calibration screw (on the back of the pen...opposite the LCD readout),
- they were very jumpy (couldn't have ANY metal around, including jewelry, notebook rings, etc.),
- and overall, we ended up replacing a lot of 'bad' pens.
- Additionally, despite claims, they were not waterproof, so if submerged too deeply into the water...well, you can guess how well they functioned after that.

With this in mind we began testing other products that were both affordable, but still met our acceptability limits. About 5-6 years ago, we decided to switch to the Oakton Conductivity Tester from Hach (#2845500, $81.39). Yes, they run about $15 more than the Pocket Pal model, but they are a much better pen.
- They are MUCH easier to calibrate (push buttons under the battery cap),
- has a 'hold' button allowing you to take your reading and hold it making it easier to read without standing on your head in the water,
- has an auto-shutoff (saves tons on replacement batteries),
- are waterproof (with rubber O-rings preventing water from entering circuitry),
- has a replaceable tip/probe preventing the replacement of the entire pen (Hach # 2845900, $51.25).
- it comes in its own plastic box that you can put a little silica pack in during storage to help prevent rusting of the probes.
- One thing to keep in mind is that the probes are coated with a thin layer of oil to prevent rusting during storage, so this must be cleaned off prior to using (easily done with rubbing alcohol and a cotton ball).

The long and short of it is we are happy to have made the switch to the Oakton pens. They test well, are 'relatively' inexpensive, are much easier to calibrate and use, I believe we are getting better data because of it, and saving money in the long run b/c we are replacing fewer pens.

Hope this helps!!
Chris

Christopher M. Riggert
Stream Team Program
Volunteer Water Quality Monitoring Coordinator
Missouri Department of Conservation
P.O. Box 180
2901 W. Truman Blvd.
Jefferson City, MO 65102-0180
Phone: (573) 522-4115 ext. 3167
Fax: (573) 526-0990
Chris.Riggert@mdc.mo.gov
www.mostreamteam.org

On Fri, Feb 12, 2010 at 10:49 AM, ginger north <ginger@delawarenaturesociety.org> wrote:

Candie - We too have been using the Oakton TDSTestr for about 7 or 8 years - different models as they update them we now use the model #11 and we have had no problems with them at all. They are very easy to use and very stable as Chris mentioned. So I would second that recommendation.
Ginger North
Science Science Coordinator
Delaware Nature Society
PO Box 700
Hockessin, DE 19707
www.delawarenaturesociety.org
ginger@delawarenaturesociety.org
302-239-2334 ext. 100

On Fri, Feb 12, 2010 at 3:27 PM, Revital Katznelson <revitalk@sbcglobal.net> wrote:

I also found that the Oakton conductivity and TDS meters worked well. However, one of their models had a very thick layer of plastic around the thermistor, and the temperature (which affects the temperature-compensated reading) took a long time to equilibrate. As I recall, I added a sentence about this to the Clean Water Team's SOP-3.1.3.1 (available at
http://www.waterboards.ca.gov/water_issues/programs/swamp/cwt_guidance.shtml )

Revital
510 406 8514

From: Bonani Madikizela <bonanim@wrc.org.za>
To: "csreesvolmon-bounces@lists.uwex.edu" <csreesvolmon-bounces@lists.uwex.edu>, 'Volunteer water monitoring' <volmonitor@lists.epa.gov>
Date: Thu, 11 Feb 2010 08:18:32 +0200
Subject: FW: Somerset Water Kits

Good day volunteers !

In South Africa I ‘m busy implementing a voluntary monitoring programme, called Adopt a River. Indeed I ‘m looking at simply tools for the public participation and school kids. I haveMalcom Beech of Somerset Water Kits. I strongly believe that he can answer your questions regarding electrical conductivity, which can also be broadly calculated to estimate TDS.

Enjoy your fun days in the field, we do so in South Africa !

Regards

Dik's

From: Zagry Scholtz
Sent: Wednesday, February 03, 2010 7:17 PM
To: Bonani Madikizela
Subject: FW: Somerset Water Kits

fyi

From: Malcom Beech [mbeech@isat.co.za]
Sent: 03 February 2010 05:40 PM
To: Zagry Scholtz
Subject: Somerset Water Kits

Dear Zagry

Thank you for your valued enquiry today regarding the water testing kits we supply.

We have shipped off to you a Microlife Water Quality Testing Kit plus a Microlife Water Field Kit, to assist you in establishing which kit would better serve your needs for this project.

Attached please find our catalogue (1.3 MB odf file), in which I kindly refer you to page 19 for details on the two kits.

I look forward to your feedback.

With kind regards

Malcolm

Malcolm Beech
Managing Director
Somerset Educational (Pty) Ltd
Tel : 042 - 243 2030
Fax : 042 - 243 2746
Cell : 082 314 3567

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