pH Drop Checker And How To Use It
It’s not easy to write up about Drop Checkers in a short answer so I decided make this post and use as many examples and images as possible. By the end of this article, you should know what a Drop Checker is and how to use it.
So a drop checker looks like this:
What is this thing?
As describe in a previous post, a Drop Checker is a U shaped glass container filled with a 4 KH solution and a pH indicator. The reservoir is build so that there is an opening that allows gas (CO2) exchange between the solution and the water in the aquarium. As the CO2 gasses off from the aquarium into the drop checker, the pH lowers and the color changes. By looking at the color in the reservoir, we can easily find how much CO2 there is in the aquarium.
How to use a Drop Checker?
1. The first step is to make a 4 KH solution. To make this solution, we mix distilled water with sodium bicarbonate (baking soda) until we achieve 4 KH. It does not take much to get 4 KH. Because it can be difficult to work with small quantities, we are going to make a 40 KH solution. Then, all you need is to mix that solution with more water to make it 4 KH.
0.99 gram of baking soda in 1 liter of distilled water = 40 KH
To dilute the solution and make a 4 KH solution, take a 10ml sample of the 40KH reference and add it to a 90mls of distilled water.
Tips`: You can also use sodium carbonate instead of sodium bicarbonate. To make sodium carbonate, you need to cook the baking soda for 30-45 min at 400F before weighing to remove water and CO2 in the baking soda. This will make your solution even more accurate
2. Turn the drop checker upside down and fill it with your 4 KH solution and add 3 drops of bromothymol blue (Blue liquid which can be found in low range ph test kits). Filling a Drop Checker can take a little practice. Tilt the checker slightly so the solution runs into the ball. Try to fill the ball half full, as this ensures the maximum surface area for gaseous exchange.
3. Turn the Drop Checker back over, and insert into the aquarium, making sure there is an air gap. At this point, the solution in the checker should be blue.
How do we read it?
Once the checker is in the aquarium, it will take a few hours before CO2 in the aquariums exchanges across the air gap. After 2-3 hours, CO2 in the checker and CO2 in the aquarium should be the same.
The increased CO2 level in the Drop Checker will affect the pH which will change the color of the regent.
A blue colour indicates you have a CO2 level of 25ppm or less
A green colour indicates your have a CO2 level of 26 – 35ppm
A yellow colour indicates you have a CO2 level of 36ppm or more
Why is it accurate?
To measure CO2 in water, we need to have an accurate measurement of pH and KH.
Since we know we are working with 4 KH, we don’t need to measure KH which reduce risk of error.
We also know that there are no other buffer that could influence our reading which reduce risk of error again.
The color of the solution only turns green when the optimal concentration of CO2 is achieved in the aquarium water.
Feel free to use the comment box bellow if you have any question about Drop Checkers and how to use them
Article written by Patrice Lapointe for AquariumsLife.com
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I have to admit that this post is so informative and detailed. An excellent article for all those interested in aquariums. Many of us just buy an aquarium put some fish and done. However, there is so much to do with an aquarium. Taking care of the fish, measuring CO2 levels in the water and using the right tools like the Drop Checker mentioned in this post is very important.
Great!!
That’s true, we can experiment and learn lot with aquariums. I had a look to your website, nice work!
Keeping things simple is an art. Great explanation!
Thanks!