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Randy Holmes-Farley
01/03/2006, 09:31 AM
Get ready to test your reef chemistry savvy. :)

The January Reefkeeping will have the first Reef Chemistry Quiz.

It consists of 50 multiple choice questions on reef aquarium chemistry issues. It is anonymous, but at the end you get a ranking based on your score, and you can see how others have scored in bar graph form. :D

It is a hard test, but covers things we normally discuss here.

I'll post a link as soon as it comes out (about Jan 5).

In the meanwhile, start cramming!

SeanT
01/03/2006, 11:32 AM
Sweet!

boxfishpooalot
01/03/2006, 03:12 PM
Cool, I better start cramming.

You mean I actually got to start paying attention in class now Randy :lol:

Is the test timed? If not people can look all day for the answers.

Randy Holmes-Farley
01/03/2006, 03:16 PM
You mean I actually got to start paying attention in class now Randy

If you want to be a Master or Senior Reef Chemist, yes. If you only want to be a neophyte, you can sleep in. :D

90-100% Master Reef Chemist
80-89% Senior Reef Chemist
60-79% Reef Chemist
40-59% Apprentice Reef Chemist
26-39% Novice Reef Chemist
12-25% Neophyte Reef Chemist
0-11% For heaven's sake, it's a multiple choice test!

boxfishpooalot
01/03/2006, 03:47 PM
well im sitting beside SeanT so I should at least pass :lol:

We agreed he would let me look at his paper for a couple of frags :D

Hobster
01/04/2006, 10:59 AM
Is it open book/computer? :)

Cheat sheet:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=102605

Randy Holmes-Farley
01/04/2006, 11:23 AM
In the intro, I suggest folks can do it open or closed book, and just interpret the results in light of the choice. :)

I'd try closed, then when questions seem harder, look them up if you want. :)

tokitay
01/04/2006, 11:26 AM
Hobster, Thanks for that link. Great reference info.

Hobster
01/04/2006, 12:30 PM
<a href=showthread.php?s=&postid=6420825#post6420825 target=_blank>Originally posted</a> by tokitay
Hobster, Thanks for that link. Great reference info.

Thanks go to Randy, it's all his work.:thumbsup:

Glad Chemistry is pretty much an exact science and not subject to all the controversy as some other forums.:)

Ereefic
01/04/2006, 09:31 PM
Thanks Randy for that Quiz. I'm an idiot. :hmm5:

SeanT
01/04/2006, 10:52 PM
<a href=showthread.php?s=&postid=6414523#post6414523 target=_blank>Originally posted</a> by boxfishpooalot
well im sitting beside SeanT so I should at least pass :lol:

We agreed he would let me look at his paper for a couple of frags :D
Not a problem.
After this long in the hobby reading Randy's expertly written (and at times [THANK GOD] layman written) articles I better score at least a "Reef Chemist
". ;)

Sean

Boomer
01/04/2006, 11:09 PM
Warning !!

On our discussion and review of the test, Habib and Water Keeper only made Reef Chemist :D

Ereefic
01/04/2006, 11:22 PM
<a href=showthread.php?s=&postid=6426547#post6426547 target=_blank>Originally posted</a> by Boomer
Warning !!

On our discussion and review of the test, Habib and Water Keeper only made Reef Chemist :D

:eek: I'm going to have to start taking Waterkeepers and Habibs replies with a grain of salt. :lol:

mbbuna
01/04/2006, 11:35 PM
can i have a retest??? i got 54%:)

Randy Holmes-Farley
01/05/2006, 06:14 AM
Here's the test:

http://reefkeeping.com/issues/2006-01/rhf/index.php

Good luck, you're gonna need it. :D

Randy Holmes-Farley
01/05/2006, 06:54 AM
FWIW, there is a bug in one question that we were unable to fix in time:

http://reefcentral.com/forums/showthread.php?s=&postid=6427481#post6427481

DrBDC
01/05/2006, 07:36 AM
I only got a 58%. :sad2: I better study. Some of the borate q's I completely guessed at. Also I've never used conductivity or paid attention to some other concentrations.

DrBDC
01/05/2006, 07:41 AM
After I posted I saw the bug post! Woo hoo I'm a reef chemist then at 60%. \:D/

Randy Holmes-Farley
01/05/2006, 07:44 AM
Great job!

Amphiprionocellaris
01/05/2006, 09:35 AM
I got a 50, And I'm supposed to be a chem major:(! It might be time to go over to the dark side... I mean, the biology dpt:D.

DrBDC
01/05/2006, 10:02 AM
I should have used those study pages linked up above. Just like studying for a test, you know what you know and concentrate on the items you don't. I had no idea it was going to be that tough or I would have. Most tests you can give an intelligent guess without even knowing the subject and get a 75, not that one!!

Hey! And what's wrong with the Biology dept? :lol:

Randy Holmes-Farley
01/05/2006, 10:26 AM
It might be time to go over to the dark side... I mean, the biology dpt

My initial scoring scheme had the lowest score be "Maybe try biology", but before Ron Shimek parted ways with RC, he was the science editor of the magazine, and he nixed it. No sense of humor, I guess. :lol:

Hobster
01/05/2006, 12:16 PM
That was hard, no slacking in your class! Just enough easy ones to make us feel like we know something :)

54% and no cheating (did use the calculator though.)

Were questions 48-50 really necesssary?:D I tried the "always "c" and snagged one!:lol:

Randy Holmes-Farley
01/05/2006, 12:26 PM
I tried the "always "c" and snagged one!

:lol:

Didn't like those last few, huh?

Habib
01/05/2006, 12:39 PM
<a href=showthread.php?s=&postid=6426547#post6426547 target=_blank>Originally posted</a> by Boomer
Warning !!

On our discussion and review of the test, Habib and Water Keeper only made Reef Chemist :D


Hmmm, I scored Senior Reef Chemist and at that time there were more bugs. ;)

Nevertheless, it is a difficult test but a very nice one. :)

Bojan
01/05/2006, 04:24 PM
Thanks Randy for that Quiz.

WaterKeeper
01/05/2006, 04:54 PM
<a href=showthread.php?s=&postid=6426547#post6426547 target=_blank>Originally posted</a> by Boomer
Warning !! On our discussion and review of the test, Habib and Water Keeper only made Reef Chemist



But I was able to persuade Randy to change enough answers, on the Beta version at least, in my favor to move closer to the Dutch Boy. :D

<a href=showthread.php?s=&postid=6426615#post6426615 target=_blank>Originally posted</a> by Ereefic
:eek: I'm going to have to start taking Waterkeepers and Habibs replies with a grain of salt. :lol:

How many ppm of salt are in a grain per gallon? ;)

Seriously, it is a hard, but fun, test and thanks to Randy for writing it. :thumbsup:

Next he plans on asking questions on the chemical composition of nematode poop. You need to read Ascaris S**t Hits the Fan (http://reefkeeping.com/issues/2005-12/rs/index.php) first, however.

:p

piercho
01/05/2006, 05:27 PM
At 64% I felt like a DA but after looking at the distribution I guess its relative. Some of you weiners store far too much data in your noggin -> % buffering capacity of borate in NSW, COME ON!! Productive and fun. I wonder what project I should bill that piece of work-day to? JK!!! I promise!!!

ReeferAl
01/05/2006, 05:27 PM
Since I only had 15 min for the test I only acheived Senior Reef Chemist. When I read through the answers though I wouldn't have made Master no matter how much time I had taken without going open book. My days of working that hard at tests are over though.
Allen

DrBDC
01/05/2006, 05:45 PM
Don't they have a little guy with a different finger up than the thumb? :lol:

ReeferAl
01/05/2006, 07:30 PM
:D Chemistry was my undergrad major, although it's been a looong time.
Allen

marie
01/05/2006, 09:58 PM
Ok, I know my score doesn't measure up to you guys, but your all chemists and I'm just a lowly dog groomer.

So to toot my own horn, I actually got 40%:bounce2:, no open book (or peeking in the chemistry forum) and I haven't lurked in here in months :lol:

Thank you Randy. You reach more people then you think :D

Randy Holmes-Farley
01/06/2006, 09:38 AM
I actually got 40%

That's great! :)


I'm glad folks like the quiz.

I'm a little surprised there haven't been many dispuites yet over the answers. Boomer, Habib, and Tom argued endlessly in the beta testing (probably trying to boost their scores). :D

DrBDC
01/06/2006, 10:01 AM
After watching all the fighting in the forums and not being able to get involved, they have to vent sometimes!

WaterKeeper
01/06/2006, 01:27 PM
What I want to know is, OK Randy, you changed questions so I could get a better score; can I stop taking that new drug you have? My palms are growing hair and my lips have blisters, isn't it time to say I has "adverse reactions"?

:mixed:

boxfishpooalot
01/06/2006, 01:35 PM
wk you crack me up :lol:

WaterKeeper
01/06/2006, 01:45 PM
You mean that stuff that Randy gave me is crack?

:D

Randy Holmes-Farley
01/06/2006, 03:28 PM
No, it's an experimental drug for increasing coral calcification rates. How do your bones feel?

DrBDC
01/06/2006, 04:32 PM
You're distributing that now? I'll take some, I've been waiting since you mentioned it. I'll try it on my grandmother too, she has osteoporosis. :D

tcottle
01/06/2006, 06:31 PM
Sigh - I only made 50% Apprentice Reef Chemist But I did catch the error in the answer in question 34. That made me feel better - when I started catching the errors in the text books in college I knew that I was beginning to master the material.

Guess you are going to have to stick around RC a little while longer :D :D :D

ReeferAl
01/06/2006, 08:53 PM
<a href=showthread.php?s=&postid=6436889#post6436889 target=_blank>Originally posted</a> by Randy Holmes-Farley

I'm a little surprised there haven't been many dispuites yet over the answers. Boomer, Habib, and Tom argued endlessly in the beta testing (probably trying to boost their scores). :D

Well, there were a pair of questions I wondered about. In question #14 the correct answer was that borate provided 23% of the buffering of NSW at pH 8.2 In the explanation to question #18 regarding alkalinity you said:

For natural seawater, all of the contributions other than carbonate and bicarbonate are very small compared to the first two terms. All of these others combined comprise less than 4% of the total at pH 8.0

I knew borate played a larger role at higher pH, but does a change from pH 8.0 to pH 8.2 really make that much difference?
Allen

Boomer
01/06/2006, 11:48 PM
Tom

to move closer to the Dutch Boy

Are you sure you want to be closer to a "Dutch Boy" :lol:

Randy

Boomer, Habib, and Tom argued endlessly in the beta testing (probably trying to boost their scores).

Hey, that was not the reason. Ok, it was for Hab's and Tom's reason

Allen

I believe the the answer is in the terms, TB ( Total Borate) vs. BA (Borate Alk). Borate Alk is around 82 umol kg -1 at 8.2 pH but the TB is a round 415 umol kg -1 at 8.2 pH. Based on a table I have;

pH
.....8.0................8.1................8.2...............8.3


BA...55.5...............67.5..............81.6.............97.7

CA...2275............2263...............2248...........2332

If you now go look at another table at 8.2 pH for species


HCO3- ..................1777 umol / kg

CO3--......................225

B(OH)4-..................104

OH-.........................7

organic matter.......5-12

HPO4- + PO43-.......3

MgOH+...................2

H3SiO4-.................nil

NH3.......................nil

Randy Holmes-Farley
01/07/2006, 05:13 AM
Well, there were a pair of questions I wondered about. In question #14 the correct answer was that borate provided 23% of the buffering of NSW at pH 8.2 In the explanation to question #18 regarding alkalinity you said:

For natural seawater, all of the contributions other than carbonate and bicarbonate are very small compared to the first two terms. All of these others combined comprise less than 4% of the total at pH 8.0

This is a complicated question. :)

Alkalinity is provided by several things, but mostly by bicarbonate. As the pH drops from 8.5 down and down, to say, 7.0, there is no decrease in bicarbonate (in fact, a slight increase). So the contribution of bicarbonate to alkalinity is always high.

Borate, which is the form of boric acid/borate that contributes to alkalinity, declines steadily in concentration as the pH declines from pH 8.5 (because more and more is in the boric acid form).

So it's contribution to total alkalinity is pH sensitive, and is lower at lower pH.


Buffering is a different story. As the pH drops, both of the primary buffering combinations, HCO3-/CO3-- and B(OH)3/B(OH)4- decrease in capacity as pH is lowered.

Since they are both dropping as pH is lowered, the RELATIVE contribution of borate to pH buffering pH is not lowered as fast as its relative contribution to alkalinity.

Here's the relevant section on buffering from my borate article:

'In the case of normal seawater at pH 8.2, b = 0.19 meq/L/pH unit for the boric acid/borate system, and 0.63 meq/L/pH unit for the bicarbonate/carbonate system. These values are additive, and result in a total buffering of b = 0.82 meq/L/pH unit. Under these conditions, the boric acid/borate system provides about 23% of the total buffering, while the bicarbonate/carbonate system provides about 77%.

If the pH of normal seawater is raised to 8.5, the total buffering is b = 1.2 meq/L/pH unit, or about 40% greater than at pH 8.2 (because both systems are closer to the pKa). At this pH, the relative contribution of the two systems to the total capacity is only slightly different than at pH 8.2, with 20% from borate and 80% from carbonate.

If the pH of normal seawater is lowered to 7.8, the total buffering is b = 0.42 meq/L/pH unit, or about half that at pH 8.2 (because both systems are farther from the pKa). At this pH, the relative contribution of the two systems to the total capacity is also only slightly different than at pH 8.2, with 29% from borate and 71% from carbonate."

ReeferAl
01/07/2006, 09:00 AM
<a href=showthread.php?s=&postid=6443165#post6443165 target=_blank>Originally posted</a> by Boomer
Allen

I believe the the answer is in the terms, TB ( Total Borate) vs. BA (Borate Alk). Borate Alk is around 82 umol kg -1 at 8.2 pH but the TB is a round 415 umol kg -1 at 8.2 pH. Based on a table I have;

pH
.....8.0................8.1................8.2...............8.3


BA...55.5...............67.5..............81.6.............97.7

CA...2275............2263...............2248...........2332

Boomer,
But from the table, at pH 8.2, BA/BA+CA = 3.5%. The question asks:
Approximately what percentage of the buffering of natural seawater is provided by boric acid/borate at pH 8.2?
The answer is 23%. Now I realize that "buffering capacity" and "alkalinity" are not truly synonymous, but 3.5% to 23% is a big difference. Using the numbers you give for species concentrations and the formula from question 18, I come up with a contribution to TA from borate of about 4.4% at pH 8.2. Unless I am missing something, the only way this makes any sense to me is the difference between "buffering capacity" and "alkalinity".

Borate, which is the form of boric acid/borate that contributes to alkalinity, declines steadily in concentration as the pH declines from pH 8.5 (because more and more is in the boric acid form).

So it's contribution to total alkalinity is pH sensitive, and is lower at lower pH.


Buffering is a different story. As the pH drops, both of the primary buffering combinations, HCO3-/CO3-- and B(OH)3/B(OH)4- decrease in capacity as pH is lowered.

Randy,
Is this because "buffering capacity" refers to the ability to resist pH changes in either direction as opposed to alkalinity which relates only to the resistance to pH decreases?

Allen

Randy Holmes-Farley
01/07/2006, 09:59 AM
[B]Is this because "buffering capacity" refers to the ability to resist pH changes in either direction as opposed to alkalinity which relates only to the resistance to pH decreases?[?B]

Partly.

The buffering capacity is meant as resistance small changes in pH, in either direction (the value for a tiny change is the same in either direction),

Akalinity is a measure of the acid needed to drop the pH all the way to 4.2. Bicarbonate to carbonic acid is the biggest part of alkalinity, but it doesn't really kick in until down in the 5's to resist drops (or rises) there, and that effect is not noticed up in the 8's.

ReeferAl
01/07/2006, 10:57 AM
Randy,
I was thinking about the difference in definition between alkalinity and buffering capacity and had made that very connection. I was just going to post my "revelation" but I see your prompt answer beat me to it. Thanks.
Allen

Randy Holmes-Farley
01/07/2006, 11:17 AM
You're welcome.

Happy Reefing. :)

Boomer
01/07/2006, 11:33 AM
Allen

Ok you are on line ;)

Did you try this

Borate Alk is around 82 umol kg -1 at 8.2 pH but the TB is a round 415 umol kg -1 at 8.2 pH.

and I left out from that table TA = 2330 umol kg-1

415 / 2330 = 17.8 %

Yes it is all a confusing mess at times :lol:

boxfishpooalot
01/07/2006, 02:28 PM
I did it again and got 76%, reef chemist. Although I would not call myself a chemist in any way :lol:

WaterKeeper
01/07/2006, 02:31 PM
It's about time Boomer had a "Revelation"; Say, Hallelujah!
:D

Boomer
01/07/2006, 11:02 PM
I will have a bigger "Revelation" at the end of May :D

DarkXerox
01/08/2006, 03:24 AM
<a href=showthread.php?s=&postid=6428782#post6428782 target=_blank>Originally posted</a> by Randy Holmes-Farley
It might be time to go over to the dark side... I mean, the biology dpt

My initial scoring scheme had the lowest score be "Maybe try biology", but before Ron Shimek parted ways with RC, he was the science editor of the magazine, and he nixed it. No sense of humor, I guess. :lol:

Haha hey I'm a bio major and I got 60% :p All that Ochem paid off a little I guess.

Randy Holmes-Farley
01/08/2006, 06:23 AM
:thumbsup:

Good job, DarkXeroX!

Mighty Quinn
01/11/2006, 03:33 PM
Hey Randy,

Great test! Wow, that was tough. I decided to take it closed book and only got 64% (although, I must admit that I used the online calculator that you kindly provided a link for). As with many others who have taken this test, the borate and general alkalinity questions really got me. I guess I need to reread some of your articles.

While I was disappointed in my score, I was somewhat comforted when I saw the statistics. Ahhhh, it takes me back to my college days....Ride the curve, baby!

Quinn

Randy Holmes-Farley
01/12/2006, 06:29 AM
Hey, 64% is good! It might have been higher as there may still be a scoring bug in Q 34. :)

wife no likey
01/12/2006, 09:10 AM
I got ripped off on 11! It didn't say that it automatically compensated for temp! :)

i'll take apprentice though :lol:

Mighty Quinn
01/12/2006, 09:25 AM
<a href=showthread.php?s=&postid=6482360#post6482360 target=_blank>Originally posted</a> by pennilessreefer
I got ripped off on 11! It didn't say that it automatically compensated for temp! :)

i'll take apprentice though :lol:

I agree, Question 11 is a bit bogus. I knew that most conductivity meters automatically compensate for temperature, but I assumed that the point of this question was to show that we know that temperature compensation is important.

Q

Randy Holmes-Farley
01/12/2006, 11:23 AM
Yes, Tom debated that one in the beta testing. :D

My challenge to him was to ask if there were any meters ever sold that did not incorporate it. None showed up. :)

But, we'll be nice. Give yourselves an extra 2 percentage points!

DrBDC
01/12/2006, 12:29 PM
Keep giving them away! I'll be Master Reef Chemist if I wait long enough without even studying more!

WaterKeeper
01/13/2006, 11:12 AM
WaterKeeper drags out his 25 year old YSI "Magic Eye" conductivity meter and awards himself 2 extra points for finding one without a ATC. :D

Randy Holmes-Farley
01/13/2006, 11:15 AM
:lol:

OK, go for it!

wife no likey
01/13/2006, 12:09 PM
Thank you . . I sort of felt cheap ;)

Randy Holmes-Farley
01/14/2006, 03:50 PM
I sort of felt cheap

Sort of what you'd expect, being penniless. :D

wife no likey
01/14/2006, 08:15 PM
lol. .I like to call it "frugal" :)

clink
01/14/2006, 11:10 PM
I got 50%, I have been reading about reefs and marine fish since Aug. of '05 or so. It seems maybe I sould start my own reef and continue my apprenticeship.
thank you,
Clink

Randy Holmes-Farley
01/15/2006, 06:27 AM
Great job!

Starting your own reef sounds like a good idea. :)

rick rottet
01/15/2006, 12:02 PM
48
closed book, no calculator
not accounting for the bug in #34 (50)
not accounting for the trick in #11 (lol) (52)

Randy Holmes-Farley
01/15/2006, 12:31 PM
:thumbsup:

Good job. I'll have to make the tricks less obvious next year. :D

jdieck
01/18/2006, 04:12 PM
Hey Randy, great quiz. I got convinced to stay with mechanical and electrical engineering although a 70% closed book will be enough to keep my parameters stable. At least I got the ones with the calculator right! :lol:
BTW I also got busted on 11. Temperature was my choice.

Randy Holmes-Farley
01/19/2006, 05:53 AM
great quiz

Thanks. :)

I guess 11 should have been written better, but as long as you knew the principles, take the points!

although a 70% closed book will be enough to keep my parameters stable.

:thumbsup:

That's a very good score. :)



At least I got the ones with the calculator right!

:lol:

natual
01/20/2006, 12:41 AM
Hi randy,
Great questions! Lots of them tell me I need to brush up on my chem.

Oh well thats what you get when your a biologist working at a pharm plant as a Chemist.

Anyway,
Question 11. great question I know your right, But 'off the cuff'
D: is correct to if you took into account 20C water and calibration of conductivity meter was done at 25C.
I do conductivity, everyday the variation 2.14%/1C or so... No ATC
(USP...Grrr) and there you go. Plus I think you will agree the algorythms that are programmed into the handheld 'reef' units might not be that accurate. Plus cell constant... (no reef unit has that I am aware of) I am rambleing...
Understandable, at saltwater ppm your change isn't much.

I got a 64% (w/o corr. for 11 if I was kinda right) marine environmental biochemistry grad school here I come hopefully next year!

:rollface:

Randy Holmes-Farley
01/20/2006, 10:06 AM
I got a 64%

:thumbsup:

Good job. :)



What conductivity meter do you use? The same ancient one that Tom dug up to find one that doesn't have ATC? :D

FWIW, I agree that the corrections may not be perfect, but they are not bad. Mine seems pretty constant if I let the same water sample cool down from tank temp. Mine uses a correction designed for natural waters (at least, that's the option that I elected it to use).

WaterKeeper
01/20/2006, 10:24 AM
<a href=showthread.php?s=&postid=6545016#post6545016 target=_blank>Originally posted</a> by Randy Holmes-Farley
The same ancient one that Tom dug up to find one that doesn't have ATC? :D


:lol:

But the old YSI had a dial to adjust the cell constant at least. :D

Actually Natural, most hobby meters don't have different sized cells available for purchase so don't include a selectable cell constant. The old YSI was designed for use in everything from distilled water to the Dead Sea so there were a wide variety of conductivity probes that could be used on it. I think it even had a switch to allow one to use the new "micro siemen" units that were being introduced back then. ;)

natual
01/21/2006, 08:41 AM
<a href=showthread.php?s=&postid=6545016#post6545016 target=_blank>Originally posted</a> by Randy Holmes-Farley
I got a 64%

:thumbsup:

Good job. :)


What conductivity meter do you use? The same ancient one that Tom dug up to find one that doesn't have ATC? :D

FWIW, I agree that the corrections may not be perfect, but they are not bad. Mine seems pretty constant if I let the same water sample cool down from tank temp. Mine uses a correction designed for natural waters (at least, that's the option that I elected it to use).

I use a Fisher Accumet AB30 w/ ATC shutoff, I am not allowed to use it in my line of work. The USP doesn't allow ATC in there measurements since USP 23. It is a two cell as a 4 cell doesn't have the accuracy and precision that is required for our needs (.09uS-1.5uS) on average.
It does allow for factor of 10^ changes, TDS, uS,mS,ORP, pH(I think), temp, etc..
Separate probe for temp.
I have never heard of being able to set a cell constant, and actually I am not sure if you would want too. Cell constants tell you abs. val. of variation in reading. More of a check/correction in result than calibration setting.

Aquakeeper, thats funny "new measurement" microsiemens!:lol:

Thanks by the way;)
It was late and off the cuff.

Good line of questions, even for someone with alittle background in the field.

Randy Holmes-Farley
01/21/2006, 10:34 AM
I have never heard of being able to set a cell constant, and actually I am not sure if you would want too.

Many units do allow cell constant adjustment, such as some of the microprocessor controlled units from ThermoOrion:

"What are the differences in the calibration techniques for Orion Conductivity meters?


Orion Conductivity Meters have various calibration techniques depending on the model including Autocalibration, Direct Calibration or Manual Calibration.

The Autocalibration function found on many meters allows the meter to recognize the value of Orion Conductivity standards automatically. This is a quick and convenient calibration technique to determine the conductivity probe's cell constant.

The Direct Calibration technique requires the user to enter the temperature corrected value of the conductivity standard and the meter will determine the cell constant.

Alternately the Manual Calibration allows the user to adjust the cell constant value until the standard reads the appropriate value for its temperature.

For all calibration techniques, Orion conductivity standards are recommended. It is important to assure that fresh aliquots of standard are used each time. It is not recommended to reuse conductivity standards for calibration as this can lead to erroneous results."

from:

http://www.thermo.com/com/cda/service_support/detail/0,2231,155,00.html

Cody Ray
01/28/2006, 03:12 AM
I think 43% is pretty good for a highschooler! Of course the year of chemistry and the salinity/density lab I did in Marine Bio today probably helped ;)

DrBDC
01/28/2006, 05:01 AM
Marine bio in HS? Wow, we didn't get a choice like that. Although I'm not sure if I was interested in anything but female biology at the time. We just had biology and Human Anatomy and Physiology if you were good enough in bio to get in.