I'll try my best to explain in English, and the original Chinese version will be followed after this.
Chlorine, known as Cl2, is heavier than carbon dioxide, known as CO2. You can figure it out by calculating its molecule weight. However, when I trying to build a farm for Lily Flower, Cl2 is floating above the CO2, which is unexpected and inconsistent to the known fact : - (
The Chinese version of the problem description is followed:
氯气（Cl2）比二氧化碳（CO2）要重。你可以通过计算它们的分子质量来得到这一结果。然而，当我试着修建一个 Lily Flower 农场时，氯气却漂浮在二氧化碳上方，让人感到出乎意料，而且和事实不符。
By the way, I really appreciate your dynamic fluid system, nice job, but I observed a little problem: the calculation seems based on the weight of the gas. In fact, gas pressure is based on the number of molecule instead of weight, when in the same temperature and volume, which means regardless of the kind of the molecule, oxygen, hydrogen, carbon dioxide, whatever, the same block with the same pressure and temperature should possess the same number of molecules, even though there're several kinds of them. (refer to the equation: PV=nRT, P stands for pressure, V stands for the volume of the gas, n stands for the amount of substance, which you can see as the number of molecules, T stands for temperature and R is a constant.) I know it's almost impossible to make one block contain multiple kinds of gas at the same time for programing, but it's doable to make the gas fit the physical laws when there's only one kind of gas in the same block. You can just ignore this because it does not affect the balance of the game.
Another problem is not related to the gas weight, it's about chemistry. When water electrolyzer works, there should be two volume of hydrogen and one volume of oxygen produced. Maybe the problem does not exist because the gas pressure is calculated by weight as mentioned above.
Just mix CO2 with Cl2, and you will see the bug.