First off I hope everyone had a great Thanksgiving break!
If you read Andrew’s previous posts regarding the project, you would know that we have decided to scrap all of the samples we have extracted DNA from and start from the beginning. This is so we will have water chemistry data collected at the same time as DNA is collected thus providing the most consistent and accurate data.
On Tuesday, we received a portion of our water chemistry kit, which tests Hardness, Sulfites, Alkalinity, Iron, pH, and Chloride. We decided to do a practice run on a couple of the tanks so we can familiarize ourselves with the reagents as well as fine tune our sampling procedure. The results are listed below:
Freshwater Tank A
Hardness Test: 93 ppm CaCO3
Sulfite Test: 2 ppm Na2SO3
Alkalinity Test: 90 ppm CaCO3
Iron Test: No detectable amount
pH: 7.3
Chloride Test: 20 ppm Cl-
Saltwater 1088
Iron Test: No detectable amount
We learned a couple of important points through this test run that will speed up our water chemistry sampling process in the future. For every single test we did, we started using the high concentration detection procedure, but found all of the concentrations in the tanks were extremely low, and had to redo it using the low concentration detection procedure. For our real samples that we will hopefully will be taking in the next week, we can save reagents and time and just jump right to the low detection procedures. We also noticed that the Hardness and Alkalinity tests detected the same molecule (CaCO3) and also had similar concentrations and have thus decided to use only one of the tests. (I will get back to you with the chemistry behind this reasoning, which I didn’t really understand). For both the Freshwater and Saltwater Test, we were not able to get a detectable amount of Iron and will likely scrap that water chemistry test. Lastly our pH meter results were a little different from Russell’s highly sensitive pH meter (pH=8.3) that takes continuous measurements and Tweets them. (Eisen is probably going to like the idea of that!) We will either scrap our pH meter and just use his or will have to verify if our pH meter is giving is accurate readings, by putting it in solutions of known low acidity. This is just an idea of mine, not sure if it’s a good way to check for its accuracy.
That’s where we are in the project as of Tuesday. I will get back to you about the differences between Hardness and Alkalinity and also update when we start taking samples again!
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Jonathan Eisen's Lab 
Well, yes, I like the Tweeting pH meter. But that is probably a more useful feature for field studies than in this case …
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Actually we were thinking more of the outreach value. Students using the classrooms where the tanks are located can follow the pH meter and tweet to it when they cause disturbances to the system. Plus we’ll be able to track a series of perturbations to the system (new organisms added etc.) since the aquarium folks have agreed to tweet anytime they mess with the tank.
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