I don't know how much to dose or how many times a week. I have Flourish, Excel, and Iron. I used Fluval Shrimp Substrate. 12 hour photoperiod w/ 2 Fluval 13 watt lights that are about a month old. Tank has been up for about a month, maybe a bit longer. I have duckweed, DHG, purple cabomba, a dwarf lily, 1 stem of water sprite, and a floating plant I can't name. My Cabomba, water sprite, duckweed, unkwnown plant, and dwarf lily are doing well. My DHG is yellowish and just doesn't look healthy. I have some root tabs as well that I can put in.