|Byron ||11-08-2011 08:04 PM |
Welcome to Tropical Fish Keeping forum. Nice to have you with us.
Now, to your questions. I am not exactly sure if you meant you are adding a fertilizer that contains iron, or if you are adding an iron-only product in addition to a basic general fertilizer. There is a big difference.
Iron is not necessary as an individual nutrient unless you are running a high-tech planted tank system, with CO2, daily nutrient dosing (of all necessary nutrients) and higher light. Iron is only a micro-nutrient, and an excess of iron can be very detrimental to plants and fish. Iron is after all one of the "heavy metals" that are very toxic to all life. If you are running a low-tech or natural system, with no CO2 diffusion, then a complete nutrient fertilizer is all that is necessary, once or twice weekly.
The levels of heavy metals in a good complete liquid fertilizer are minimal, balanced for the needs of most aquatic plants. I doubt a test made for aquaria would detect iron or much else. But there is sufficient iron in a product like Flourish Comprehensive to nourish a tank of plants for a week.
On the Eco-Complete substrate. According to the manufacturer, CaribSea, this product contains iron, along with other nutrients. These release over time to feed the substrate-rooted plants. I've not used EC myself, but some other members here have, so if they see this they will likely contribute. I have used Flourite, I have had a tank with this for 7 months now, and I still need to dose liquid fertilizer or the plants show signs of weakening. I cannot say if EC and Flourite are similar in this respect. I have read good reviews and bad reviews of EC on plant groups.