Went searching for fertilizer for steam plants that have roots in the substrate and was recommended to get this http://hueyhung.com.tw/E/body.php?web=14&PNo=2006080042 by Natural Aquarium.

Anyone has experience using this, interested to know if there are any heavy metal substance in this as the description does not say anything. Thinking of introducing some Yamato to clean out my driftwood.