Hi, I'm just starting L2 and the first thing I need to do is understand how to test the pH of soil (and of course, what kind of soil it is). Rather than just get a little soil testing kit which has a limited number of uses, I'd like to get a test tube rack, some test tubes, some barium sulphate, and some of the indicator solution. I also need a 2mm sieve. Is there anything else that I should get, and where / what is the best source (at a reasonable price!)? Can someone please post urls for me - I'd rather go online than in-store.... I found some barium sulphate on Amazon, but it says it's 97% (https://www.amazon.co.uk/Barium-Sulphate-250g-Including-Delivery/dp/B07C6J9XDG/ref=sr_1_2?crid=34F6QBTKW93BQ&keywords=barium+sulphate+powder&qid=1564416764&s=gateway&sprefix=barium+sulphate%2Caps%2C284&sr=8-2) is this ok, and how much will I need? Does it go off once I've opened it?
Thanks in advance!