Don't know about what's happening to your plants but 1/2 tsp is not 30 mls. 1/2 tsp is 2.5 mls. 30mls is 2 tbls.
Any aquarium weights used these days in the US are a zinc alloy, no lead. But that isn't to say that some of lead couldn't sneak in from another country.
you can treat the fish in quarantine with maracyn 2.this is a broad spectrum antibiotic.from what you have described,it sounds like septicemia.you said
Alright. I've settled on a stand. Found this one online and fell in love with it. Here's a quick sketch with my new coloring app. (Had to play with it,
i have newly set up tank (6 weeks) its a 110gal TALL (48Lx 19W x 30H)
set up info:
Substrate- Safe Tsorb