Flourish Iron is a highly concentrated (10,000 mg/L) ferrous iron (Fe+2) gluconate supplement. It should be used in those cases where the iron requirements exceed that which can be delivered by Flourish at the recommended dose or signs of iron deficiency appear (such as short and slender stems or yellowing between veins.) Plants are able to much more easily derive a benefit from Flourish Iron than from EDTA-iron sources because all EDTA iron is in the ferric (Fe+3) state. Since plants require iron in the ferrous state, additional physiological energy must be expended in order to extract the ferric iron from EDTA-iron and then convert it to the ferrous form. It contains no phosphate or nitrate.
DIRECTIONS: Use 1 capful (5 mL) for each 200 L (50 gallons*) or as required to maintain about 0.10 mg/L iron. For smaller doses please note that each cap thread is about 1 mL. Use MultiTest: Iron test kit to monitor iron concentrations. Use as needed to combat signs of iron deficiency (usually seen in new growth) which include: chlorosis (yellowing) of tissue between veins and short and slender stems.
Q: Why do I need to use Flourish Iron if I'm already using Flourish?
A: Iron is an important nutrient in the planted aquarium. In order to maintain an adequate iron concentration it should be dosed on a fairly regular basis (daily). Flourish should be dosed less often (semi-weekly or weekly) since its components are not rapidly depleted. Daily dosing with Flourish can lead to unwanted algae growth. By having these supplements as separate products, the hobbyist can add Flourish Iron every day and not risk unwanted algae growth while still adding the necessary level of Flourish on a less regular basis.
Q: When I added your Flourish Iron product to my tank within a few minutes the water turned milky and was full of what looks like calcium specks. I have been adding CO2 to my tank for some time now and have buffered the water with bicarbonate of soda to counteract the low pH reading I get with CO2 injection. After I filtered the white stuff out with a diatom filter, when I checked for iron it was almost non-existent. If it is the bicarbonate is there something else I can safely use to buffer the water? What is causing this reaction, and have you heard of this happening to anyone else?
A: This is a peculiar response. Flourish Iron does not normally cause cloudiness unless used excessively, and even then the cloudiness is very mild. Since the cloudiness was caused by a white precipitate, as you confirmed by testing, it is not an iron precipitate. It is also unlikely to be a direct carbonate precipitate. I suspect that your water is exceptionally hard (contains a lot of calcium/magnesium) and that you may also have a high alkalinity (carbonate content), and that the addition of Flourish Iron (by an ion competing mechanism) pushes the calcium/magnesium carbonate in the water beyond saturation, resulting in the precipitation of calcium/magnesium carbonates. Even without the addition of Flourish Iron, do you sometimes see a white (chalky) film on the surface of the water? If so, that would support the presence of high calcium/magnesium. You may want to test your water for calcium/magnesium and alkalinity. If you experience problems growing certain plants, that may also suggest excessive hardness, since many plants prefer soft to only mildly hard water. Do you see any cloudiness when adding bicarbonate? If you have to frequently add bicarbonate, you may be using to much CO2. Regardless, however, I expect your calcium/magnesium hardness is the culprit. While this is nothing to panic about, if it should prove to be the case, I think you would do better to dilute out your water with some kind of soft water, such as DI, RO, or rain water.
Q: The Pet Warehouse advertisement stated that the Seachem iron test kit was great for planted tanks and REEF tanks. I was disappointed to read in the iron test kit directions that natural seawater levels of iron were at the lower limits of the iron test kit. Is this kit usable for reef tanks? If the level of iron in natural sea water is at the lower limits of the test kit, why is it being advertised as great for reef tanks?
A: Pet Warehouse has apparently over hyped an otherwise true statement. The fact that our kit measures only the lower limit of iron concentrations in seawater is not a limitation of the kit, but in fact a limitation of iron's solubility in saltwater; iron is just really not (or barely) soluble in saltwater. To get iron into seawater at a reasonable concentration, it must be strongly chelated, and our kit will measure this strongly chelated iron; it just requires a longer testing period (detailed in the instructions). So if your are dosing your tank with a strongly chelated iron, our kit will measure it. If you are not dosing and are just curious how much iron is in the tank, the kit will tell you that also, but it is going to be basically next to nothing.
Q: I've got a 40 gal heavily planted tank with Fluorite substrate. I started dosing with Flourish Iron a few weeks ago due to pale leaves on pennywort, etc. The color has improved. I'm adding a capful every day to the tank; an hour after adding, my tank shows no iron with the Hagen test kit. Are the plants grabbing the iron? Or is it precipitating out somehow.
A: I am confident that the iron is being consumed. If it was precipitating out of solution, you would notice a white chalky haze to your water and a white colored coating to your aquarium walls, heater, filter, etc.
Our Flourish Iron is a very different type of iron. Our's is bound to a carbohydrate that is very easily metabolized by your plants. Most of the others on the market are chelated iron supplements and your plants has to expend large amounts of energy to get the iron from the chelate to be able to use it.