[jones57742]

lgl:

enc has much more experience than I do "so please keep that in mind here".

I believe that what we are both trying to address here is

1) very high nitrite concentrations (and more importantly the very high ammonia concentrations associated therewith) are lethal over a very short period, typically extending from a few hours to a few days and
2) high nitrite concentrations (and once again more importantly high ammonia concentrations associated therewith) are toxic to fish: ie. the fish will not "be happy fish" and their lifespan will be significantly reduced.

Examples:
How long would you survive breathing 10% air and 90% cigarate smoke (ie. this is an analogy to fish in a tank with very high nitrite and ammonia concetrations ).
Do you believe that being in a bar room which is 50% cigarete smoke and 50% air for 10 days would affect your life expetancy (ie. this is an analogy to fish in a tank with high nitrite and ammonia concetrations ).

My concern with respect to the 80% WC is the adverse effect to the biological filtration media.

The following are IMHO and are based on emc's posts (emc: I "never figured" that significantly high nitrite concentrations would exist):

If your nitrite concentration is 1.0 mg/l or greater then forget the serious adverse effect to the biological filtration media and perform an 80% WC;

If your nitrite concentration is between 0.15 and 1.00 mg/l then forget the adverse affect (which will be minimal) to the biological filtration media and perform a 30% WC immediately and then start the protocol as set forth in my previous post and

If your nitrite concentration is below 0.15 mg/l then proceed in accordance with my previous post.

I have absolutely no experience with goldfish and, hence, for sure no experience comingling goldfish and tropical fish. I will research this topic today or this weekend and post
BUT
Based on your signature the cost of a 50G tank, an HOB filter, a heater/thermostat, and a thermometer is "nothing" compare to your grandson enjoying his goldfish
ie. please humor me, hustle one up and start cycling.

TR

BTW:
One of these days it will be your turn to expend the time necessary to prepare the posts which emc and I have based on our experience.