Hi Chris. When l first started to look at biochar, l bought a bag of lumpwood charcoal, and tries smashing it down into very small pieces. Hard work. Thus, l decided to look at making it with wood shavings. A lot of questions were being asking which l also wanted answering. l spent a lot of time finding out. When l started making my own, there is a difference, and you can feel it. And there is a slight difference in the way it is manufactured. With biochar all the carbon enhancing gasses are burned off, but l suspect some of these escape when making charcoal. l'm 100% sure of that, bu there is a difference in temperature. l have looked at the two sites and what they sell is useable as far as l am aware. l couldn't see any prices but hopefully it will be a lot cheaper than carbon gold. l prime mine with liquid manure (from soaking alpaca manure [because l can get it] in a bag), diluted worm pee from my small wormery, and liquid sea weed fertiliser. Much the same as added to carbon gold. As for the amount to use? Well l reckon that the Mayan Indians added it to their soil for 2 thousand years, and to make a soil depth of 2 m, must have taken a hell of a lot. So add it as you can afford it. Making my own with a £60 outlay lets me produce about 200 litres at 35p a litre including fertiliser. This year l added heavily to my row of runner beans. Single row of 12 feet and at the rate of 2 1/2 litres per foot (shallow trench). nothing else added, Not quite doubled last years crop which had a few more plants, but plenty more to come. By the way, not all of the £60 outlay will need to be replaced, so the next lot will be cheaper,