There is several different types of silica, some are pretty cheap, some are expensive. A guy that works at my local hydro store said that gh armor si, (potassium silicate) is not immediately available to the plant. He said that after about a week the roots break it down, before its available, but its pretty cheap. Power si is expensive and it is also potassium silicate. I know there is other formes of silica, ie monosilic and others. So whats the best silica for a hydro res. flood and drain buckets? As much as i want gh armor si to work i want something that i know is working even if it costs more.