I’ve made mine by using some lettuce and powdered egg yolk dissolved in water in a jar. It’s been sizzling under the sun, lighted during the night, for almost three weeks now (well ventilated too). I’ve read that it’s supposed to turn greenish, instead it’s yellowish. I’ve only used 1 leaf of lettuce (half a palm size) and a quarter of egg yolk. Maybe the egg yolk dictated its color but I want to make sure that I have protists partying there and not the bacteria that they feed on. I don’t have a microscope to verify. Do any indications, like color of water or demography of debris or smell, exist to help me know?