|I recently rescaped the 55, by the way. Goodbye Pleco!|
Well, I'm sorry, I'm in an intellectually polyamorous relationship with Chemistry AND Physics, but by now, I'm sure you all get the gist of what I was trying to say. Recently, I've been reading Dr. Derek Lowe's excellent chemistry/pharmacology blog on Corante, which I recommend to everyone who, like me, did enough chem in school to have wanted to do it professionally, but never took the chance to actually do so. Reading the blog reminded me that once upon a time, I used to blog about science too... until I started blogging mostly about Aquaria and amateur aquaculture.
Whether your interests lie properly within biology, or you're an armchair chemist, aquariums can be like a playground. While I would never advocate experimentation on live fish, lots of indirect experimentation happens with the water chemistry, and of course, water can always be removed from the tank to work on. Aquarium water is far from pure, containing all sorts of fun ionic compounds. One day, I might desalinate some, and I'm willing to bet I'd wind up with a whole lot more than sodium chloride staining the vessel I use to do it.
The drop tests used for most parameter detection are properly titration experments. If you took Chem 121 (or whatever high-level-but-grade-12-appropriate Chemistry would have been called in your area), you remember titration as a horrendously complicated little process used to derive dubiously useful information about the solutions.
Aquarium tests, however, are quite simple. So's titration, as long as you're good with your apparatus and know what the hell you're supposed to be doing. Which ones are titration? Hardness and calcium.
All the others are technically titration as well, but are open-ended because they contain (or create) an indicator in solution that reacts more or less strongly depending of the concentration of the ions you're interested in. That's why the iron test won't detect chelated iron without the second reagent - the second reagent frees the iron ions into solution to be exposed by the reagent.
Why can't I order the reagents at work? If I had my way, my aggressive testing and monitoring routine would apply to all the tanks in the store. As it is, I already want to do full work-ups on a few of the trouble spots... something I'll probably do tonight. The other reason, of course, is that I know which reagents are which and would probably feel no shame at all in routinely experimenting with them in inadvisable ways.