With regards to where I get my supplies, we do not seem to have many choices. I tried to get some of the basic chemicals such as potassium bicarbonate or chloride from local chemical suppliers, but first of all most of them only carry industrial grade, not food grade, chemicals, and secondly, they are set up to only deal with businesses and do not wish to deal with individuals.
That narrows our options to only the health food outlets and manufacturers. Hence, I shop for all these chemicals such as magnesium salts (malate, ascorbate, citrate, aspartate, etc.) as well as most other supplements online at iHerb.com which carries a very large selection of products from many manufacturers such as NOW Foods, which happens to be one of my favorites because of their quality and reasonable prices and their no-gimmick and no-nonsense approach, something very rare with most other companies. In fact, I am going to try their fulvic acid product now that it seems to be within Ted's specs.
I have not gone after the food-grade hydrogen peroxide yet, and I would not use the regular 3% solution available at Wal-Mart or 99Cent stores because it contains traces of tin, phosphates, and nitrates-- I actually contacted Aaron Industries which makes these products and they told me that the concentrated solution they purchase from another manufacturer contains these stabilizers although they themselves do not add anything more to it other than purified water for dilution.
For sodium bicarbonate, I use the regular Arm & Hammer baking soda that you can find in any grocery store. I contacted them also, and they told me that they do not add anything to their baking soda although they do not have any chemical analysis of the soda ash (a mined mineral deposit) from which they make their baking soda by adding carbon dioxide in a solution--i.e., no additives or stabilizers. I hope that this information answers your question. Please let me know if you need more information. Have a great week and keep up the good work. Also thanks for all the help.