Well yeah, that too. lol
I'm also generally not big on mixing any of the above due to personal aesthetic reasons. I have seen this type of set up referred to as "fish soup", and I typically tend to agree. Having said that I have one tank that contains a hyper dominant P. polleni, a single T. meeki, a single A. nigrofasciata, and a pair of super red BN plecos. And this is in a 6ft 125 gallon tank. A strange mix, but the only fish that have been able to survive with the larger male polleni. As much as I would have loved to keep this tank a strict biotope type set up, the only way that is going to play out is if the polleni has the tank to himself, which for me would have been too boring. I love the fish, so I did a work around with fish outside of his continent that have been tough enough (so far) to survive his fits of temper.
As far as sterilizing a tank, I wouldn't have used ammonia. I would have used bleach, then ran high salinity for 24 hrs or more, then let everything dry out.