i saw that one too, but i had no way to measure the water or to weigh the baking soda accurately. i did have a food scale that weighs ounces and grams but it was way too inaccurate for something this delicate. its good for measuring ounces... but into grams and it is no good.
a dollar bill in good condition should weigh one gram. i put a dollar on this scale and it did nothing. i stacked 5 bills on this thing and it still said zero.
6 grams is about 2 teaspoons. i probably couldve tried to measure it this way and used a measuring cup for the water. Instead, i just eyeballed the whole mixture, filled a red cup half full, dumped in about a gram of baking soda, filled another cup half full. i just diluted the baking soda water until i could test it at 4dkh. it works.
from what i have read, less airspace between the drop checker solution and the tank water means a faster reaction. more airspace requires more time to eaqualize the gas concentration of the checker to the concentration of the tank. this is why tom barr made up a checker that used a gas permiable membrane. it has no air gap. the checker responds a whole lot quicker.
im not really concerned about the rection speed, or else i would be on the quest to find a gas permiable membrane and make my own checker. i just want something to tell me how much is too much co2 before the fish do. the price was right, plus the thing looks kinda cool.
anyway, i also read that filling less solution into the drop checker bubble can yeild to faster reaction times, i think the logic behind this is; less solution it has to equalize the quicker the ph can change, therefore the color... can anybody confirm this?