Join Date: Aug 2010
Location: Charlottesville, VA
Old 4dkh solution, starts out green
At least two years ago I made my own 4dkh solution using baking soda, distilled water, and a milligram scale. Not too long after I broke my drop checker and was too lazy to order a new one.
I'm getting more involved in my aquarium again and have finally acquired a new drop checker. I still have the same 4dkh solution that's been stored in a glass jar with a metal lid on pretty tight. I've tested it and it still registers as 4dkh.
However, when I add my bromothymol blue to it, I get a green color. I thought maybe there's just some dissolved gasses in there somehow messing things up and let some of the solution sit out in a shot glass for a few hours. Sure enough, it's now blue.
I guess my question is, is this anything to be concerned about? Does it matter if I don't let it sit out before adding it to the drop checker? Should I let the whole jar sit for a day or so with the top off to let it reach an equilibrium with the atmosphere again? Searching around, I haven't been able to find anyone else ever having this problem.