CS>question..how to get the ppms you want

[Teri323]

Since l am not going to be making my own CS..but purchasing a cs generator..l 
am wondering how do all the ones making their own CS know what ppm they are 
getting consistently? if l buy a generator..can l know for sure l will be 
getting the ppms that l want? also..does anyone have a small amt of  cs they 
could sell me until l am able to get the generator?  experienced CS'ers 
please give me your advice and wisdom..thankyou teri.