A very kind scientist at McGill sent me samples of four different strains of rotifers, along with the formula for the medium he keeps them in. The rotifers look so lively and healthful that I decided to buy the chemicals and mix up some of his medium. The problem is that while I need a few milligrams of this and a couple of grams of that, nobody sells the stuff in quantities smaller than 500 grams of this and 1kg of that. So at the end of the project, I have almost the entire container left over, and because it came in a form that is so concentrated as to be toxic if swallowed, it all has to be treated as toxic waste. Iron-chloride is not very toxic, but if you swallow 500g you would be very unhappy. So what I will probably end up doing is mixing lots of extra solution, basically making artificial pond water, because that does not need to be disposed of as toxic waste.
I was complaining about all this to some colleagues, who replied that this is a perennial problem, and that almost any time one does lab work, one has to budget for disposal of the left over chemicals, because one can't buy them in small enough quantities. The College of Chemistry on campus has a chemical reuse library for this purpose (drop off unused chemicals with out paying for disposal, pick up extra chemicals without buying a whole container) but they don't allow people from other departments to participate, even if we ask real nice.
I looked through the various suppliers and ordered the smallest quantities possible, even when it cost more.
How thoroughly wasteful and silly this whole system is.