Not sure reheat your saying. The 4dkh solution should be around 7 ph.
However, looking at the kh/ph co2 chart, it is about PH 6.6 for 4dkh?1) Add 59.7 milligrams of baking soda to 0.5 L of RO/DI water for 3.98 dKH. Fully dilute.
2) Add the contents of this mixture to the drop checker, then add a couple drops of Bromothymol blue to the drop checker.
The perfect yellow (shade, reaction between Br. Blue and CO3) is 30.0 ppm CO2.
It seems close to what the chart is. PH 6.6 is green in color when at 30 ppm for a 4dkh solution.The colors in the chart are not what the drop checker color should be. The colors in the chart are just a reminder of the range of CO2 concentration you're in: low, good, or high.
But Wet's calculator says it should be yellow?With a 4dKH/brom blue solution, at 30 ppm your drop checker color will be solid green. Ish.
Might have read wrongly that it should be lime-green or yellowish in color.1) Add 40.8 milligrams of baking soda to 0.5 of RO/DI water for 2.72 dKH. Fully dilute.
2) Add the contents of this mixture to the drop checker, then add a couple drops of Bromothymol blue to the drop checker.
The range for "green" in this drop checker is 12.9 - 32.5 ppm CO2.The perfect green (shade, reaction between Br. Blue and CO3) is 20.5 ppm CO2.
3) Add 86.8 milligrams of baking soda to 0.5 of RO/DI water for 5.78 dKH. Fully dilute.
4) Add the contents of this mixture to the second drop checker, then add a couple drops of Bromothymol blue to that drop checker.
The range for "green" in the second drop checker is 27.5 - 69.1 ppm CO2.The perfect green (shade, reaction between Br. Blue and CO3) is 43.6 ppm CO2.
If both drop checkers are green, you have 27.5 - 32.5 ppm CO2.