Date: Thu, 03 Mar 2005 16:58:42 -0700
From: Richard Schrader
To: “Volunteer water monitoring”
Subject: [volmonitor] Hach DR 2500 vs colorimeter 890, what seems best for volunteers?
I work for River Source, a company in Santa Fe, New Mexico that works regionally designing and managing volunteer monitoring projects. My partner, the NM Department of Game and Fish has funds to purchase some expensive spectrophotometers for the secondar school program, New Mexico Watershed Watch (go to the Programs menu at www.riversource.net to see more about this). We’ve used the old DR2000 for many years now and need to upgrade or buy something else that’s cheaper (the new model DR2500 costs around $2,300 plus standards, etc.). Their colorimters work pretty well is seems at a lower cost but they can’t be calibrated regularly.
Do any volunteer program managers have words of wisdom for us folks with lots of flowing rivers for the first time in years? My questions include:
1. Can students really get repeatable data from such a sensitive instrument as the DR2500? Why not buy something that at least the glass ware is relatively cheap?
2. The colorimeter is more portable and uses the same reagents at the old DR 2000’s, many of which are still chugging away. Perhaps it’s time to move away from big budget items like the DR2500 and move to something the program could support with less money.
Your thoughts are appreciated…
2300 West Alameda, A6
Santa Fe, NM 87507
Date: Fri, 04 Mar 2005 09:10:18 -0500
Subject: re: [volmonitor] Hach DR 2500 vs colorimeter 890, what seems best for volunteers?
We have done some testing of the Hach 890 colorimeter on nitrate and phosphate and did not find that it performed as well as the Hach 2010 that we had at the time. Although these tests were by no means exhaustive, the 890 seemed to give on average higher results than expected (we used standard solutions to conduct these tests). In fact we prefer the Hach kits to the colorimeter. We use a Hach 4000 in our lab now (which is quite expensive) and it gives the best results of all. If you’d like the data on the experiments we did let me know.
Lauren Imgrund, Director
The Alliance for Aquatic Resource Monitoring (ALLARM)
Date: Mon, 07 Mar 2005 10:01:10 -0500
From: Linda Green
Subject: RE: [volmonitor] Hach DR 2500 vs colorimeter 890,
what seems best for volunteers?
Before you purchase your equipment it is important for you to consider what your students’ data is being used for, which is what you seem to be doing. Is the data used primarily for educational purposes? Is it being used to document existing condition? Is it being used to pinpoint problems for follow-up investigation? Is it being used as a part of River Source’s ongoing data collection regime? Depending on how the data and results from the instrument are being used should certainly affect what you ultimately purchase. I won’t try to guide you on specifics, but lately I have seen the costs of some multi-parameter probes and instruments going down, but on the other hand relatively expensive, required, annual maintenance by the manufacturer increasing. Depending on how much you are monitoring and where, I still, in many cases, prefer monitoring kits. For one thing, it can give students more of a sense of the chemistry involved to get a result and the fact that there are a lot of variables involved in obtaining data. But with lots of samples at lots of sites at a frequent sampling interval, instruments sure can make life easier.
This summer professional monitors using an expensive multi-parameter probe to monitor the water quality of Narragansett Bay actually came and borrowed one of our $50 LaMotte dissolved oxygen kits to use alongside their probe to make sure the probe was working properly! It wasn’t.