Re: testing for Iron
I'm glad that you are wanting to start using an iron supplement, as it plays a very important role in the planted aquarium. Since you mentioned that you might have a deficiency, here are the signs to look for: chlorosis of tissue between veins, stems short and slender, mostly affects young leaves.
To address your question about iron test kits. I would not go to the length of saying that they are all inaccurate and not to bother with them. As a matter of fact, they can be very accurate as long as they are compatible with the the type of iron you are testing for. There are indeed different types of iron that are supplemented to an aquarium. The 2 main types of iron used in the aquarium are chelated iron and non-chelated (free) iron. Chelated iron is in the ferric state (Fe3+) and must be reduced to the ferrous state (Fe2+), which is the preferred state for plants. In doing this reduction, the plants have to expend a great deal of energy. Our Flourish Iron is already in the reduced Fe2+ state and allows the plant to readily take in the iron almost immediately without using any energy.
So, of course, with the different types of iron, there is a need for different test kits. If you are using a chelated iron supplement then you will want to make sure that your test kit measures chelated iron. If you are using say our Flourish Iron, which is not chelated, then you will want a test kit that measures non-chelated or free iron for an accurate reading. Whether one is preferable over the other, I guess that will depend on what iron supplement you are using. Our MultiTest: Iron kit measures both chelated and non-chelated iron, so there is no need to worry about inaccurate results. I do want to make you aware, however, that since our Flourish Iron is bound to a carbohydrate that is very easily metabolized by your plants, more likely than not, it will not register on a test kit, even after you dose it. This is because it gets utilized immediately, but I can assure you that it is being consumed by your plants. If you would like to read more about our Flourish Iron or our Iron test kit please follow the links below:
Also, here is a link to a very insightful thread written by the owner of our company about the benefits of ferrous gluconate iron over iron EDTA (chelated iron):
I hope this information was helpful and please let us know if you have any additional questions.