Here's a thread I found when planning my aquarium. It spells everthing out pretty thouroughly.

http://www.african-cichlid.com/Structure.htm

PS: Even though you can calculate the weight of an aquarium filled with water, don't forget all of the rock you will be putting into it, the stand, the sump, surrounding furniture,... every once in a while people passing by, taking a look...(maybe a few when you're having a party)... Alot more to consider than just the aquarium itself. Irregardless, most homes are built to the above MINIMUM standards. However, if you are planning on an aquarium which exceeds the minimum standards, then please refer to your household insurance for guidance. ;-)

Riggs.

Sorry don't know much about home construction. I have a 144G on hardwood over an unfinished basement with no problems. I would think you'll be ok.

As far as finding the direction of the floor joists in the area you want the tank try this......Go to the closest floor heating/AC register, take the grill/insert out and look to see which direction the duct comes from.......if it either runs left or right that is the direction your floor joists will be running parallel with the wall, if the duct runs back towards the middle of the room the joist will be perpidicular to the wall.
May not be 100% full proof but close.

jorjef that is genius mang!

Is the hardwood already installed? If so, I thought that hardwood floors had to be installed perpendicular to the floor joists, no?

FWIW, they're installed parallel in my house..

well FYI globaldesign has his 250 gallon on his upper floor plus the sum :-)

Hardwood flooring should alway be installed perpendicular or diagonal to the floor joists. This is what I was told by a saleperson that sells hardwood flooring

Not necessarily. I think it's just "better" to install perpendicular but not "necessary". Or maybe depending on age of house or subfloor material it might become necessary.

http://ca.answers.yahoo.com/question...2080410AAR7alg

The only point I really wanted to make is that it's better to check/confirm before acting on assumptions, particularly when it's easy enough to get a definitive idea where the joists run.

I was trained that it should be installed perpendicular if possible, but if it is new hardwood over old hardwood, to run the new stuff at 90 degrees to the old.