On Mon, Nov 9, 2009 at 6:45 AM, Delpapa, Cindy (FWE) wrote:
I have been asked by a volunteer based monitoring group., (monitoring freshwater and estuary waters) for recommendations for a reliable, accurate, easy to use and reasonable upkeep/calibration costs pH meter (or other alternatives for getting accurate pH data). Does anyone have experience, por and con, on any of the following or have suggestions on a good meter/strips. Many thanks for any insight you can offer. Hanna Instruments basic (“Educational”) bench top: HI 207 or “pHEP” (Electronic Paper versions): HI 98107, HI 98128 or the portable one: HI 98121Sper Scientific the inexpensive hand-held models (“Basic” and “Advanced”)
Hach – the IQ120 Mini-Lab
and Whatman – pH test papers – (many different vvarieties)
Cindy Delpapa, River ecologist
MA Div of Ecological Restoration
From: Stepenuck, Kris [mailto:email@example.com]
Sent: Monday, November 09, 2009 10:23 AM
Our group uses Oakton Acorn pH meters and they seem to work well in side by side testing.
Date: Fri, 13 Nov 2009 10:12:57 -0600
From: Chris Riggert
I don’t have personal experience with the pH methods you listed below. But the Missouri Stream Team Program has been using Hach’s Pocket Pal pH Tester (Cat.# 44350-01) for many years, and runs about $60 list price. It does have its drawbacks (no auto shut-off, bulb and wick must remain moist, occasionally bad batch w/ faulty circuitry, small screw tends to get lost quickly, isn’t really waterproof, etc).
However, it is relatively inexpensive, easy to calibrate, and has QAQC’d well over the many years we’ve been using it. When there have been issues, Hach has been very good to work with in getting replacement equipment sent. We instruct our volunteers to perform a two point calibration within 12 hours of their sampling event, and also provide them with the pH 7.0 buffer solution (Cat.# 22835-49) and 10.0 buffer solution (Cat.# 22836-49).
I mentioned it QAQC’d well. Our acceptable limit for us is plus/minus 0.2 pH. While these pens are probably not as accurate/reliable as the more sophisticated meters used by MO DNR staff, they are much cheaper and provide more accurate/reliable results than the pH strips, etc. As with every piece of monitoring equipment, proper care and QAQC of what you are using goes a long way in getting usable results.
All depends on what their objectives are, how much error they can live with…and probably most importantly, how much $$ they have to spend.
Hope this helps!
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
Date: Mon, 16 Nov 2009 10:51:32 -0500
From: “Schenk, Ann”
Like Chris, I have no experience with the Hanna brand meters, but ALL electronic pH probes need to be kept moist because they rely on electric differentials between the highly saturated salt solution or gel inside the probe and the outside world. If the probe dries out, the bridge between inside and outside is broken. Think of it as mechanical osmoregulation.
As to recommendations, try calling the tech folks at Ben Meadows. They carry many company’s meters,are a ‘siste’ company to Lab Supplies, and might be able to give you some sort of bulk discount. Contact info is on the Ben Meadows website.
Natural Resource Biologist III
Maryland Department of Natural Resources
580 Taylor Ave., C-2
Annapolis, MD 21401