i was battling bacterial septicima in my tank for a good 2 years. i could not get rid of it. it only affected my tropical fish not the loaches. i tried mycin, metronidazole, kanaplex, aquadoxy, nitrofurizone, furan 2, fungus clear, acriflavin, formalin. none worked.
i tried this stuff called tmp sulfa. i had some results using the triple sulfa available at the local fs. but it was so expensive that i stopped using it.
someone told me that this triple sulfa can be toxic if you don't do the proper water changes. this is what i did.
it solved my fin rot and the bacterial septicima and nothing else would over a 2 year course of treatments.
i treated the recommended dose and did a 25% water change for a 10 day dose. after 5 days the symptoms started to lighten on the fish. after 2 weeks, the visible signs were gone for the symptoms. both fish are doing well now with no issues. otherwise, i lost about 15 tropical fish over a 2 year period from this nasty stuff. i tried everything everyone recommended. none worked. it might just be my particular situation. or whatever is in my tank, but for me this stuff worked great. and it filters out easy with charcoal.
i also vacuumed my gravel about 2 times weekly. not the entire tank just in 3rds so i didn't stir up too much nastiness. ive got my tds in my tank about 180 and the water is about 130 after the water conditioner.
this blog has some useful information. this is just my personal experience. take it with a grain of salt. i also used those test strips to check the parameters on a bi daily basis.
http://aquarium-medictions.blogspot.com/
here is where i got it. i only got a gram of it. tmp sulfa on this page.
http://www.nationalfishpharm.com/products5.html
their shipping is over priced but they have bulk meds available.
im scared to use maracyn2 it crashed my qt tank bio filter when i was treating fish and killed them all.
i can't constantly monitor that type of thing when i work all day. so i get scared of bacterial meds that kill the bio filter.
get a tds test meter and see how the tds in your tank is. if its over 300 thats not so great.
i think the legal limit in drinkin water is 500. im not 100% sure.