So this is a bit of a doozy.
In November, my husband and I moved 1500 miles from Georgia to Texas (he's military). I had to take down my 29 gallon and put Tanwyn into a little travel container and we went.
At the time I had plain sandbox sand as substrate, and because it was so wet, compacted, and heavy, I ended up throwing most of it out. We move, set up the tank, and I got some Fluval stratum. I had some java ferns that really took off, and for Christmas I got some new live plants to add; duck weed, red root floater, and dwarf hair grass.
My first mistake was not quarantining the new plants, or giving them a bleach dip. I got so many additional snails, then worms. I've learned since, but yeah, not good. I dewormed the tank. Everything went away (except the snails) for a bit, then a few weeks later there was an explosion of both. Then I noticed all my plants were dying off, even the duckweed! I removed Tanwyn to the hospital tank, threw out the plants, and drained out the water completely, and left the substrate to dry out as much as possible in an attempt to remove the worms (and snails as much as possible). Added in faux realistic plants. Everything was fine.
Then, towards the end of January, I noticed hydras, then Tanwyn started splashing the top of his tank, then he started tail biting. I quarantined him again. And then... he didn't get better.
Can adding plants to an established tank cause a crash? I'm wanting java ferns and a few things in the new tank but I don't want to go through this whole rigamarole again. The new setup is dirted with a gravel cap, natural hardscape, and two baby pothos. I have a journal with all the new tank details.
The old tank when I first added in the plants.