I have it on my chard yes. I have been treating with 1 % solution. I don't have access to distilled water. I have been using ordinary tap water. I can leave the water to stand to remove the chorine but more than that idk. I do not have a dehumidifier or an air conditioner. I can gather rain water but I imagine that to be equally full of chemicals from the polluted atmosphere of my town.But I do have an unmotivated meter.
Yes, in 500ml it would be 1.25g:
1.25/500=0.0025, or .25%
Boiled water has the same minerals and impurities that it had before it was boiled (without the bacteria), so that's not the same as distilled. Distilled water is made by boiling water and capturing the steam, which leaves behind anything dissolved in the water.
Do you have PM?
I regularly recommend your 1 % solution, so it is good to have a full understanding of what I am advising people to do.