Culture experiences with Echinodorus plants
Formerly being land plants, which withdrew themselves into the ecological niche swamp and/or open water, the requirements of the Echinodorus species are not all too large. For this reason, nevertheless they learned to maintain even in unfavourable situations compared with other plants.
For a successful culture in tanks, good lighting conditions are important. Although some species, as for example to Echinodorus horizontalis, exist in the deepest darkness of the jungle roof, they are not at all light shy in the aquarium. In contrary, with intensive lighting they grow quite well. Too much light cannot be given, when sufficient carbon dioxide supply is existing in the aquarium. But the premise of sufficient CO2-supply is decisive, since without it alga-problems will rise. If there is not enough free CO2, some species try to get the necessary carbon for the assimilation from the carbonates, as lime sediments on the leaf surfaces demonstrate. But carbon dioxide deficiencies decreases growth substantially, because carbonate assimilation needs more energy. Also the increasing pH value impairs the growth.
The second important condition for a perfect growth is sufficient CO2-supply. The often expressed opinion, that there is no need of additional CO2, is only partially correct. Carbon dioxide concentration and light conditions are always to be seen in close relationship. A healthy growth can be observed with less light and less CO2, but it does not obtain the optimum.
Like all the other swamp plants, Echinodorus get a substantial part of its nutrients with its roots. Therefore it is particularly important to offer sufficient nutrients in the soil. Preventing nutrient consume over the roots, the plants would not grow well, only as a cripple or would not grow at all. Although Echinodorus is able to take in a part of its nutrient household over the sheet surface, this is not sufficient for its high demand.
The substrate, in which Echinodorus is growing, should therefore contain enough macro nutrients, like nitrogen, phosphorus, potassium, magnesium and calcium, and the micro nutrients, iron, manganese and in addition copper, zinc and boron are vitally necessary. Therefore the lower part of the substrate should contain loam in the sand/gravel. Loam contains less or more clay which has the very important characteristic to absorb nutrients and make it available to the roots. If you would improve the nutrient supply you can add some wood ash to the loam, because the ash contains the most important nutrient elements like potassium and iron but does not contain nitrates and phosphates. My mixture is one volume part ash to 5 volume parts of loam. One part of this mixture can be given to 5 parts sand or fine gravel and deposit as lowest layer into the tank, then cover it with a layer of washed sand or gravel.
In existing aquariums you can add nutrients to the substrate with small balls formed out of a loam/wood ash mixture (5:1) and dried in the air, until they are hard and then press them into the root area of the plants. Absorption water the loam balls becomes soft again and the plants can take up the nutrients with their roots.