Yeah, I found that, I but I am not sure weather you put it in powder form, or weather mix it in water? Or does it make a difference?
Okay, so how do you test the levels of co2?
This may sound stupid, but what is K+, PO4, and Fe? NO3 is Nitrates, right?
My best bet would be you mix it in the water. I don't think there is any dry fert that you just pour the correct amount of powder in the tank. If you want to test how much C02 is in the water, get a drop checker. You will also need a 4dKH solution with that and use the pH testing liquid from your test kit to get the methenamine blue. Here is a link to the one I got
Aquarium CO2 Glass Drop Checker Test 4oz 4DKH Liquid Optional | eBay
It comes with the 4dKH solution so all you have to provide is the pH solution. Here is a part of the description of the drop checker: It is made of glass, very durable. It comes with a suction cup, AND a 4dKH standard reference solution IF YOU CHOOSE. The 4dKH is 4 liquid oz. and the bottle has a flip squirt top. You cannot get correct readings unless you fill it with this 4dkh liquid. DO NOT use aquarium water.
The 4 oz bottle will last a VERY LONG time. It is almost as big as a pop can as you can see.
You will also need pH drops, I do not sell those. You must use drops from a regular pH liquid test kit (normal range 6.0-7.4). API test kit is a good one.
INSTRUCTIONS:
To get the liquid into the bulb, partially fill the horn with liquid, 5 ph drops, and hold the suction cup tight against the top, and shake it vigorously, until some liquid gets into the bulb. Do NOT let the liquid touch your skin, or it will affect the pH and you will get inaccurate results.
Wait a few hours then check the color. If it is still blue, CO2 is low; if it is green, CO2 is good; if it is yellow, CO2 is too high
It is much easier if you use a curved syringe, just like the ones they give you when they pull your wisdom teeth.
K is potassium, and K+ may be some potassium ion, PO4 is your phosphates and Fe is Iron. Yes, NO3 is nitrates.