Thanks DarkBlade! I will try that when I have a little more experience in this. For now, I think I'm going to have to buy the drop checker from ebay and purchase the solution SUMO sells it and put it in the drop checker. Do you think thats a good idea?
You can do whatever you are comfortable with. Since I have access to analytical grade chemicals as well as analytical glassware (volumetric flasks, analytical scales, etc), I make my own 4 dkH solution in the lab.
Oh! I don't have a drop checker yet. That's why I was wondering if you guys could tell me a good drop checker I could use. I don't have a large budget so whatever drop checker that is best for its price would help me out a lot.
It doesn't really matter which you pick, they all perform the same function. I have some DIY drop checkers that I made for < 2 USD and they work just as well as a cheap glass drop checker I got in Hong Kong for (the equivalent) of 6 USD. I am sure these will work just as well as an expensive ADA drop checker. Here is a picture of my DIY drop checker (shameless plug!)
I see. That makes a lot of sense. Thanks for all of your advice! For the SUMO solution, I buy the 30 ppm one right?
Yes, you want a 4 dkH reference solution (which will be green when the CO2 level is 30 ppm).