Emergency

[SaraB]

My one corydora had fin rot so I'm treating the tank with melafix. I'm on the second last day of treatment and my one cory (a different one) is swimming upside down.
I did notice that my water was cloudy so a few days ago I got it tested.
Ammonia 0
Nitrites 0
Nitrates just under 20
Ph 7.5
I do weekly 50% water changes
I'm going to do a water change to see if it helps but any advise would be great.

 

[Autumnsky]

Did you have the water tested after a water change?

Poor water will for sure cause a Cory to start turning upside down. Swim bladder issues as well. I would do 2 30% to 50% pwc back to back. I had one doing that and did the water changes and it went on to live a very long life.

Too much Melafix maybe? Which pwc's could help.

 

[Autumnsky]

What is the size tank and the occupants?

Also what is the filter? Did you rinse any of the media with plain tap water, or change the filter pad recently?

 

[SaraB]

Tank is 20 gallons with just the 5 corydoras right now. I used to have 7 pristella tetras but I panicked and sold them to try and give them a better chance.
The filter is just a sponge one for now. I know I can't use carbon when medicating the tank. No I didn't rinse the filter in tap water. I was too worried about the melafix damaging any bb that I kept the same one in for now.
Too much melafix might be the problem because the only size they had was for ponds. I had to do some math to figure out how much to use. It said 15ml per 150 gal. So I'm using 2ml for my 20 gallons. Is that too much?
I'll do another water test as soon as I can.

 

[SaraB]

Nevermind little upside down guy has passed. I think i'm going to finish medicating my tank before selling my corys and then do a major clean/let my tank recycle before getting new fish.