Hey, what brand did you use, Blackstrap is the most suitable IMO. The amount was about right on, 1 TSP per Gal, but you need to mix the stuff in a glass/bowl of warm water until it dissolves and then add to res.
Well understand if you don't want to go threw it again, it is a pain to have to do damage control on your grow.
Adieu

__________________
"If what shone afar so grand,
Turn to nothing in thy hand,
On again; the virtue lies
In struggle, not the prize."--R. M. Milnes.
Hugh Miller said the only school in which he was properly taught
was "that world-wide school in which toil and hardship are the
severe but noble teachers."