One drop of MMS1 will only show a yellow color, but 3 drops will show a very dark yellow/brown color if using 50% citric acid or 4% HCL.
I would only use lemon juice as an acid activator if that is all I had, as it does not contain much citric acid. And, there is more citric acid in purchased bottled lemon juice (perhaps twice as much) than in the fresh juice of a lemon.
The juice of the lemon is about 5% to 6% citric acid
You did not say, but I assume you activate for 3 minutes. Another problem with lemon juice is that it is an antioxidant. Lemon juice will
activate MMS
somewhat, but then it will reduce the CLO2 content because it is an antioxidant, too! I know that Jim says to use 5 parts lemon juice to 1 part MMS, but I have read one
chemist
who said to use as much 8 parts bottled lemon juice to 1 part MMS.
If you can get some 4% HCL, I think you will be able to activate your MMS more fully than when using lemon juice .