I am not trying to make an issue of this. It is just way too often that you see people asking and sharing advice about stocking and in the entire conversation nitrate never comes up.
Again, I am not telling people to crowd every fish they can as long as they can barely keep the nitrate okay as long as life never happens and they never miss a water change. I am just trying to let people know there is another very important side to think about when stocking. It is not just the volume of the tank but it is also water quality. A very well maintained tank can handle more fish than an under-maintained larger tank.
If they are testing the water and the fish grow their numbers will tell them if there is a problem long before any issues come of it. They simply do a larger water change every week. They shouldn't ever need to do multiple water changes in a single week just to maintain the status quo.
My point is not to have people overstock but just to realistically think of overstocking in the right way. If they have their space, they aren't crowded, and the water quality is where it should be, they aren't overstocked. If the fish are crowded but the water quality is perfect, they are overstocked. If the tank is 'understocked' according the guides but they neglect it and never do water changes then the tank is overstocked.
"Just be sure to have a 75 gallon sump with 4 HOB's and 2 canister filters." This is not true. Filtration never compensates for a lack of water changes.
Experiments have shown that water quality has more to do with growth than volume does. it was done with discus in two separate tanks. One was something like a 20 that they did daily water changes on and the other was a 55 or 75 or so that they didn't do any on or they were only once per week. The ones in the 20 grew well, they grew at the normal rate that young discus grow. The ones in the larger tank barely grew at all, if at all. The lower water quality, not the lower volume, significantly affected their growth.
This doesn't mean the fish don't need a certain minimum of actual space, it means that it is not the 55 that keeps an oscar at 8", it is the lack of water changes that keeps it from outgrowing that tank.
The 29 and 75 example is to show that we think of a certain volume being able to handle a certain amount of fish. In general a 75 can handle a lot more fish than a 29. But if that 75 is neglected it can't even handle as many fish as a properly cared for 29. It being a 75 is no excuse to keep more fish in it when your water changes don't even keep up with what is in it now.
Definitely start with the guides, but watch your water quality too. As you get the hang of things and you and your tank progress then if you are properly maintaining the tank, the fish have their space, and the water quality allows for it, then don't let a loose guide or rule of thumb hold you back from getting more fish as long as you keep things reasonable. Whatever you do make sure you watch your water quality, it is essential no matter what else you do.
Again, sorry, not trying to start anything. Thank you for making me clarify myself, I didn't mean for it to be taken the way it obviously was by some. And I didn't mean for this to get so long.
