# Wet drophecker calculator

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3
Hi,

I was looking at Wet's drop checker calculator.

With the following inputs:
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.
However, looking at the kh/ph co2 chart, it is about PH 6.6 for 4dkh?

However at PH 6.6, shouldn't Bromothymol blue, shouldn't it be greenish or lime green instead of yellow?

Here's my Tetra Test PH test kit reference chart and my drop checker. Assuming my 4dkh solution was made correctly.

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Not sure reheat your saying. The 4dkh solution should be around 7 ph.
Not sure why Wet calculator says at 30ppm, the color should be yellow?

At 30ppm, shouldn't the color be greenish or at least lime green when using Bromothymol blue as the indicator?

Is yellow correct?
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. With a 4dKH/brom blue solution, at 30 ppm your drop checker color will be solid green. Ish.
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.
It seems close to what the chart is. PH 6.6 is green in color when at 30 ppm for a 4dkh solution.

With a 4dKH/brom blue solution, at 30 ppm your drop checker color will be solid green. Ish.
But Wet's calculator says it should be yellow?
Just realized I might have chosen the "yellow" to see option.

Using the 2 drop checker option and "green to see", it looks correct that it should be green 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.
Might have read wrongly that it should be lime-green or yellowish in color.
The first chart you posted has nothing to do with a drop checker. It's a method of determining your CO2 ppm based on your pH and KH in a tank. This is what we had before somebody realized basically how to reverse engineer that chart and what color it would give you. I blame Hoppy. Pre-drop-checker technology. It had you measure your pH, and measure your KH, and where they crossed was your CO2 ppm. The colors are there to remind you of the high, medium, and low ranges of CO2. They are only vaguely representative of the color that a drop checker would be, and possibly only accidentally at that (the white, for exampmle, should be dark blue if there was any color correlation between reality and that chart).

The second chart has nothing to do with a drop checker or CO2. It is a picture of what water at different pH's, mixed with some brom blue, would look. If your tank water, mixed with a couple drops of brom blue, looks dark blue, you have a pH in the 8 or 9 range (for example).

Once you mix your 4dKH and put the checker in your tank, you're not going to want to mess with a pH chart. It won't give you useful information. If you want to know your pH when your drop checker gets green, check your tank's pH when your drop checker gets green. Meaning, use tank water, some brom blue, and check the pH chart. It will not be the same color as the drop checker at that point *unless your tank water is coincidentally 4dKH*.

One last thing - In all likelihood, when your drop checker turns green, and my drop checker turns green, both around 30ppm, our tank pH's will be *completely different*.

Okay, one more one last thing - just so we're clear, when you first mix 4dKH with brom blue, it'll be dark blue. When you stick it in the tank and turn on the CO2, it will start moving closer to green and then possibly yellow, over a period of several hours.

Good luck!
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