I have just brought a new Reef tank and want to know if my floor can take the wieght?The sizes of the beams under my floor are 2.5inch by 7inch by 216inch (18ft) The size of the base of the tank is 30inch by 18inch and will weigh 280kg max It will be next to a concrete wall and be parallel with the beams and be resting over two beams. Thanks for any help guys and girls
That much weight is going to make your floor sag. I did the math and found that tank will exert a force of 164.26 Lbs/square foot on the floor. A force of 100 Lbs /square foot is about max.
You must be able to find the joists and they'll be 16 inches apart on center - so you'll have to put your tank just 1 inch out from each joist! Good Luck with that. By putting it close to the wall - you have added strength as the joists are tied into the concrete base of your sub floor.
The only way you can find out is to have a structural engineer calculate the load at the particular place you will be setting the tank. That being said, its probably a waste of time and money to have an engineer come to your home. You might as well just add some extra support in the basement. You can use 4x4s or jack posts. Its easier to use jack posts. You will need 4 posts and I would use a double 2x8 to create two beams to run in between the two sets of posts. You want each beam to be directly under the legs of the tank stand. This will give you more than enough support for your tank.
The beams you are describing are floor joists not beams. 2 1/2 inch by 7 inch by 18 feet is a long span for that size of floor joist. Normally the length should be no longer than 12 feet. are you sure there is not a supporting beam in the center of this span running at right angles to the floor joists. If there is no support beam about the middle of the floor joists, you should have support under the location where you intend to set your Tank. In any case you should build a platform with 2 X 4's laid across at least 3 floor joists and place the tank on them so it will span 3 floor joists, not run parallel to only 2 floor joists.
