Iv set up a new tank it's about 26 gallons iv a problem with my aranda he's been treated for tail rot but has a small white bit started on his mouth warter crystal clear 30 percent warter change done carbon out due to treatment but had to buy primafix how do I go about starting a new treatment after the fin rot treatment do I do a 50cent warter change or 30 percent leave filter in for 24 hours and start the new bit stuck thanks Kate