We rec'd it used, so the tank and filter itself are of unknown exact age but we set it up late last summer, about late August/ early September, with fresh gravel, the aforementioned cypress driftwood and some plastic plants. (It's about 2.5 feet deep on a 2'+ stand, so I wasn't confident in my live planting skills considering I'm only 5'4.) Really what I know about it is a guess - there were a bunch of ciclid stones that came with it, and iron treatment so I'm guessing it had been used for a planted ciclid tank.
When we started it, we let it go with small pinches of food about every week plus a few bits and pieces from our 5 gallon tank. It had been cycled, so I took the opportunity to switch out some decor and gravel, plus two filters that'd gotten pretty funky. (I wasn't willing to sacrifice my "bio-wheel" from that filter). We also used a bag of used ceramic media (the name escapes me - the ones that look like little circles of white ceramic) that came from the previous owners.
So when it finally started showing signs of beginning to cycle (ammonia, NO levels changing, then changing for the better and looking just alllllmost there)(and let's be honest, I'd read that it would go faster if we put a few small fish in, but wasn't willing to knowingly put in something as a sacrifice only) we bought a couple of small ryukins and the shubunkin. (Who I didn't like at first, sad to say.)
By about a week later, so now we're at about late September?, we were pleased with our cycled tank, introduced new fish, and lived happily ever after until this past couple of weeks, when Shu-Shu the oranda appeared to have a scrape or sore on her head.
I dosed, about 10 days ago, with aquarium salt. No improvement. So I bought what seemed to be the safest option for what I was now terrified might be HTH disease, Seachem Paraguard, and began dosing on Thursday. Michael Young (the shubunkin) started acting a little off on Friday or Saturday but she was also one of two definite females (Shu-Shu is anyone's guess, really) who have been getting chased for a few days. Honestly at first I just thought she was tired of being run all over the tank by the males during recent spawning or maybe was reabsorbing eggs and feeling "off" and happy to stay out of the action once spawning seemed to calm down a bit. She was eating, but at a reduced rate, and defecating in a smaller, but normal looking, way.
So by Sunday when I realized she actually seemed "listless" I was worried enough to have done the water testing, then of course by Sunday night she was gone.
The water temp is at about 69-70. I keep led lighting on during the day, off at night.
I've read some accounts of aquarium salt throwing off the cycle, and reading about others who've had a total cycle crash after dosing with other meds, though nothing specific to the Paraguard.