meant al's 1-1-1 not 3-1-1

This is a good test that I've used myself, but I think they're making it more complicated than necessary. You can calculate the exact same values by measuring the volume of the container, the volume of water required to fill the substrate, and the volume of water that drains from the substrate. There's no need for ovens or scales. In fact, it was done this way here: Soil Substrate Comparisons I did a similar test on drainage components that I've been meaning to post.

Here I use a lot of "#1 Nursery Mix" which is available by the yard for about $50. It is mostly course sand, with bark and pumice stone. It comes with a PH of 6.5 and a fertilizer with a life at 70 degrees of about 3 to 4 months. I think this is the least expensive mix, ready to use, and drains well, without compaction problems. Al

Plants can grow in just about anything if given the other conditions they require - sunlight, water, oxygen, and nutrients. But how well they will grow and produce with the least amount of input and attention by the grower when growing them in containers is entirely dependent on the media or potting soil. A durable, textural mix that is fast draining and not excessively water retentive is best for most plants but these are next to impossibe to be found premade and most are custom mixes like the 5-1-1. Something like Miracle Gro or ProMix can make do, but they are not the best and seldom get recommended by experienced container gardeners:-) And most prefer their media fertilizer free, opting to control fertilization according to the plants' needs rather than the manufacturers' assumptions.