theres no decor in the tank except sand.
Hello; In my experience sand will be loaded with organic matter. Fish waste and excess food if nothing else. Never added MB to a tank with sand so you may wind up with blue sand.
I don't really have a hospital tank to hold my jardini
Hello; I understand this.
can you test the water parameter if the water have MB in it?
Hello; Good question. At the least the MB will alter the color of the test results if using a liquid test kit. If using strips then I do not know. I do not know the answer to this.
my first time using MB and I want to do it the right way and don't want to kill the fish by doing it wrong
Hello; You were given several warnings about the MB killing off the beneficial bacteria (bb) if you added it to a display tank. Since you already did so against this advice you will have a problem. It seems very likely you will kill the bb and will be starting a new cycle from scratch later on.
There was a way to avoid this problem and I hope you did this. You could take all the media out of the filter and keep it in a bucket of tank water for a few days. Just keep it wet and throw in a bit of fish food to rot and this should keep the bb alive for a while. Then when you put the main tank back up you can replace the media in the filter. If you did not do this then you may have a problem bigger that the one this thread was started about.
Of course if there is disease in the tank then it may be harbored in the filter media.
All in all it may not make much difference what you do if the fish has black spot disease.
Black spot disease is spread by birds, and carried by snails. In freshwater fish there is no real treatment, you have to simply wait it out & make sure that the cycle cannot repeat itself. (do not keep snails with infected fish
Good luck and as stated by another it is good you have tried to help the fish. Sometimes there is not much we can do.