Opinions on floor support 240 gallon

[ReefHunter006]

I would throw a 4x6 and screw jacks in if you're looking for cheap and quick. I'm a structural engineer.

Thank you :)

 

[Donseas]

I am a General Contractor in California bay area. 2x6 Joist can only run 6 feet before being supported. So they are undersized just for a floor load. Rule of thumb is 1 inch per foot.
I am working on a new 225 gal tank. I have the same situation, 2x6 but mine only run 6 feet between foundation and midspan beam. I added 1 3/4 x 5 1/2 LVL's sistered to each joist and SDS screwed them together. I also have a LVL under both ends and mid span of tank stand under where the feet from the metal stand will be.

 

[Fiziksgeek]

I am going through this now, thinking of a 250-350 gallon tank running parallel to the joists with a finished basement below. The worst case scenario I think. I tried a couple contractors, reached out to several engineering firms, architects, even called the local building inspector to see if he had a recommendation....all with no success. The most helpful person I found was at my local lumber yard! They offer free design services for trusses and engineered wood products. I made a bunch of measurements and brought them a hand drawing with the placement of what I thought might be the biggest tank I want with the expected weight. I added bit for a safety factor and they designed me a couple LVL beams and provided all the calculation for sheer, bending, and deflection.

If the space below isn't used, or you don't mind throwing up jack posts in the space, go with the ideas above, it's a solid DIY plan. If you want to span the distance and desire some confidence with the solution, try your local lumber yard!