Additives series， used for keeping aquarium environment， are contained in an eye drop container， which is easy to supply a small amount in the aquarium. Like liquid fertilizer series， economical large volume bottles are also available for refill. * Please follow the suggested dosage amount on the instruction manual for the first time use. Then adjust the supply amount depending on the aquarium condition after getting the knack of it. ECA ECA contains rich iron and organic acid promoting the nutrient absorption process of plants. It is highly recommended for treating color-loss of plants.