I've been challenging the Warmers to show us a laboratory experiment demonstrating the effect of a 200PPM increase in CO2 on temperature and so far have rung lemons. Let's take 2 10 gallon fish tanks side by side. In the first is air. In the second we add 200PPM CO2. Here's the problem, 200PPM is less than a whiff, it's a barely perceptible increase, so how can I make sure I only add 200 PPM? (See, when the Warmers do this experiment they often put in 200,000 - 600,000 PPM but we're only going to add 200PPM.) Let's see -- how many ounces in 10 gallons? There are 128 fluid ounces to a gallon so there are 1280 total fluid ounces in a 10-gallon tank. We want to add 200 PPM, which is .02% (I said it was a tiny number) so therefore we add about 1/4 ounce of CO2, but that's liquid...how do I adjust for the gaseous state of air? Can I just drop in 1/4 oz of dry ice or is that too much by volume?