>From my experience the Test Tabs from LaMotte can be highly accurate, but
this in part depends on your method for reading the color change results.
You could use a color chart printed on a card (less accurate), a visual
color comparison devise (allows you to compare color change to an untreated
water sample - more accurate), or a spectrophotometer (highly accurate).
Another advantage of the Test Tabs is that there are fewer steps therefore
fewer opportunities to make mistakes.
For the most part, the other kits will from Hach and LaMotte (requiring
multiple steps) will be more accurate then the Test Tabs. However, there
are more steps to these tests and more opportunities to make a mistake.
Also, the wet chemicals in these kits need to be replaced regulary in order
to maintain the accuracy of the tests and the glass ware, reused in the
larger test kits, needs to be cleaned properly.
One note of caution. Be sure that when you compare Test Tabs to other kits
that they are measuring the exact same thing. This is especially true with
Phosphate. Is it measuring Ortho Phosphate, Total Phosphate, Phosphorous?
I hope this is helpful.
David Schmidt
GREEN
At 6:56 PM 10/17/97, Linda Padwa wrote:
>Hi all,
>
>I have a question regarding the accuracy of the water testing kits.
>
>I took my students on a canoe trip on Wednesday and we collected many
>samples. When we arrived back at school we began testing and realized
>that many of the results we got were probably not correct. To check our
>values I went to the Marine Science teacher and got some of the test-tabs
>she uses to check the different aquaria she has in her room.
>
>It turns out that the test-tabs gave much better, more realistic values
>for nitrates, ammonia, etc. They were also very simple to use.
>
>I am trying to decide if the test kits are more trouble than they are
>worth. Do any of you have comments/suggestions on the accuracy of the
>test-tabs vs. the Hach or LaMotte kits?
>
>Ilook forward to hearing from some of you soon.
>
>Linda Padwa
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David Schmidt, Director of Educational Services dschmidt@green.org
Global Rivers Environmental Education Network (313) 761-8142
http://www.econet.apc.org/green/ Fax (313) 761-4951
GREEN
206 South Fifth Avenue, Suite 150
Ann Arbor, MI 48104 USA
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