Sodium thiosulfate was the previous dechlorinator. Now, I forgot the name of what they use, but its a one hit miracle chemical. It breaks chloramine and binds chlorine and ammonia AND it will also chelate heavy metals. Your iron and other heavy metals in the water for plant nutrients should already be in a chelated form anyway so that shouldn't be an issue.
The pond stuff that I posted is the good stuff. Basically if it says that it can detoxify chloramines that you're good. Doubly sure if it says it neutralizes ammonia.