I’m sourcing stuff for preparing grow medium for Spirulina Algea…
Most chemicals are easy to find and reasonably affordable, or I allready have them. 2 are quite expensive and you only need a tiny bit of them to make the trace elements solution;
manganese chloride tetrahydrate > https://www.sigmaaldrich.com/catalog/product/sigma/m5005?lang=en®ion=BE
zinc sulphate heptahydrate > https://www.labshop.nl/Webwinkel-Product-234483532/Zinksulfaat-heptahydraat.html
Anyone who can help with that, can sell a small amount, maybe wants to share a purchase, maybe @reagent @niekd ?