Ummm.. no they are not, Commercial floors don't even meet that standard.

Residential floors are 40psf live (anything you put on the floor), and 15-20 dead (weight of the floor itself). Though in most cases a newer home with exceed that standard, depending on the type of joists that are used.

That said, you should be fine, but like others said, need to keep it off carpet, using 3/4" plywood will spread the load over the carpet.

Oh I design buildings for a living, so I have a pretty good idea what I am talking about.

This.
Don't cut your carpet out :neutral:
Just ensure the tank is level. I know some people will fill the tank with a few inches of water and then play with it to make sure its level, since waters flat... You can kinda measure the water line from all sides and corners until you're happy with it.
I have a piece of plywood under my stand as well.

Our house is ... 45+ years old, my tanks on the 2nd floor, against a load wall, about 80-90 gallons total system, no issues here.

Interesting. I was told that by the builder that built my house. Just goes to show you I guess. Now I'm wondering about my 2500+ tank on the main floor of my house. Good thing I have it on an outside wail where the joists sit on the sill plate.

Shows that builders don't even know.

Depending on the footprint of your tank you are probably ok., like I said, most floors evened the standard. To give an example, the typical 'I' joist is 11 7/8" deep & can span around 18' feet at 19.2" spacing. Most homes are under that spacing or span. Also strapping or drywall will increase the load they can carry, same with the type of sheathing used. Many variables go into the load caring capacity.

Well not to hijack.
My house is 8yrs old and I plan on putting a 225G with 1 1/2" steel stand on my main floor. Sump is in basement. The spot is kind of like a bay window, like where a kitchen hutch would go. I have a 144G there right now. Will I be ok? It is a weight bearing wall. Filled should be about 2300lbs

I am talking about getting him a Red Sea Max 65g. Footprint approx 38" wide by 18" deep.

Just get a piece of plywood to fit under it. Put it in place. Add a bit of water so you can level it out perfectly. You can always let it sit for a few days like that incase the carpet fibers settle or something... who knows... Then start it up. You will be fine with that size of tank in your house. People have much much larger in similar situations.