It's quite possible to maintain perfect, or near perfect water conditions in a tank.
I have 5 goldfish in a 75g and one male BN Pleco - 1 goldfish is 8.5 yrs old, and the other two are 6 yrs old, with two 3 month old ryukins.
My tap water actually has a 0.50ppm ammonia, but I also use Prime with my water changes, and I don't age the water either as I have absolutely no room to hold buckets of water for aging, so it's a python to the sink on water changes.
My tank is barebottom with no real plants (since the goldfish eat everything)
I run an Eheim Pro 3e 2078 with ceramic filter rings in one tray, substrat in 2 trays, a media bag of carbon in another (I have driftwood in the tank for the pleco but am not a fan of a heavy tannin colour), then filter floss, then a filter pad.
If I can manage that in a tank with pooping champs, it can be managed most anywhere lol