Quote Originally Posted by keith_r
i just got a free 50 gallon tank that was "home repaired" - it holds water so will probably become my hospital tank in case i have to treat any fish issues..
adding hydrogen peroxide to a system (i would think) would probably wipe out nitrification process
It depends at what concentration and many other factors.

For instance, if you set up the hospital tank and biofilter as separate areas, and of course depending on the concentration and other organic material present, you can just aerate the tank in the sun for a few hours then allow the water to run. Typically, the exposure is only for a few minutes to an hour, which means you can either do a water change or let the sun/aeration degrade the hydrogen peroxide to water.

I have experimented some using 3% hydrogen peroxide and found it to degrade quickly in the test tank I have, but the test tank seems to have a bloom of some kind of microorganism and the hydrogen peroxide definitely reacts with it at higher concentrations (I tried 1000 mg/L, it was cool to watch).