chemical testing methods

[sweetdreamfiji]

I teach a High School chemistry class. I was thinking of working up assays for the reef aquarium in my room. Do you know of a reference that gives instructions for water testing chemicals and methods for aquarium parameters? I would like to buy the chemicals and set up titrations. I have a method for alkalinity.

Thank you for your help,

Mike

 

[bertoni]

I think most of the other test parameters would be more difficult.

 

[Randy Holmes-Farley]

I agree that aside from alkalintiy, which I also use my own test, the others are much harder.

Do you have any spectrophotometer equipment available?

This thread has more:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1518421

 

[sweetdreamfiji]

Thanks Randy. I had seen that thread but several references had been added since I look at it. There was a calcium procedure if I can find the reagents at a reasonable cost.

I will keep in mind that you think they will be hard to do.

 

[Randy Holmes-Farley]

If you do come up with a good test that works well, please let us know. Most of of the kit companies, not surprisingly, won't tell us what is exactly in their products.

However, now that I think of it more, the Hach kits do generally reveal their ingredients, just not the concentrations. SO you might read over the kit instructions and refills that they sell.

www.hach.com

 

[KevChem]

I just finished teaching a course using our local lake (Lake Winnebago) water - it's not seawater, but hard as anything!

I used the Hach and LaMotte reagents with my spectrophotometers (Genesys from Fisher). My students had to find the correct chemical reactions for their lab reports.

My original procedures came from the Standard Methods for the Analysis of Water and Wastewater book (I think mine is the 17th edition).

What we did:

Potassium by precipitation using sodium tetraphenylborate with absorbance at 750nm taking the place of turbidity.

Chloride (low levels in the lake) by precipitation with silver nitrate, filter, dry, and weigh (Gravimetric analysis).

Alkalinity by pH titration (graphing pH vs. volume acid added, taking first derivative to find inflection point - tedious but great data!).

Phosphate by absorbance using the molybdate reaction (Hach reagent packs).

Calcium and Magnesium by EDTA titrations (one at pH=10 for both Ca+Mg, one at pH=12 for Ca only). We also did Ca and Mg by AA.

Nitrogen cycle compounds (ammonia, nitrite, nitrate) by absorbance and ion selective electrode (NH4 and NO3 only) methods - I made the nitrite reagent (Greiss) but used the Hach reagent packs for the other two.

I'm also setting up some of these for a local club meet in January - so I will soon have procedures written for seawater - pm if you want a copy when I have them.

Kevin

 

[jansenwrasse]

For Ca++

1N NaOH
color indicators: C8H8N6O6 (purpurate) or Eriochrome blue black
I make mine with the ammonium purpurate: 200mg ground into 200mg pure NaCl to a fine powder
EDTA: 0.01M

50mL sample of water
2.0mL NaOH sol. (pH must be over 12.0)
~.2g Color indicator salt
Titrate with EDTA

Calculating

mg CaCO3/L = [ (mL of EDTA used) x ( mg CaCO3 eqivalent to 1.00mL EDTA ) x (1000) ] / (mL of sample)

Hope this helps

I am fairly confident that this is the same procedure that Salifert uses but that is just my educated guess.