Flourish Excel is a simple source of readily available organic carbon, All plants require a source of carbon, This is typically obtained from CO2, but, may also be obtained via relatively simple organic compounds (such as photosynthetic intermediates), Since both processes occur simultaneously one can derive a substantial benefit with the use of Flourish Excel either alone or in conjunction with CO2 injection, Flourish Excel also has iron reducing properties which promote the ferrous state of iron (Fe+2), which is more easily utilized by plants than ferric iron (Fe+3), Flourish Excel is an integral component of Seachems plant products and is recommended for use with the entire Flourish line as well as our Flourite and Onyx gravels, Contains no phosphate or nitrate, Directions: On initial use or after a major (> 40%) water change, use 1 capful (5 Milliliter) for every 40 L (10 gallons*), Thereafter use 1capful for every 200 L (50 gallons*) daily or every other day, For smaller dosing please note that each cap thread is approximately 1 Milliliter, Note: The 2 and 4 L containers cap is 10 Milliliter, Do not overdose! in case of eye exposure, promptly and thoroughly wash eyes with water and seek medical attention, 2 Liter / 67, 6 fuel oz, (Treats 80000 L (21165 US Gallons)), SKU: RYLHC4984