Aha, yeah, my old place was built in the late '50s, so barring earthquakes, I think it has done it's settling.

You can get steel I-beams from Varsteel or some kind of steel supplier in the area.

This is what I mean by creating the plywood bulkhead

Start with joist
http://i11.photobucket.com/albums/a1...lps/Joist4.jpg

Add plywood layer to cover entire span
http://i11.photobucket.com/albums/a1...lps/Joist2.jpg

Repeat staggering seams
http://i11.photobucket.com/albums/a1...lps/Joist3.jpg

Repeat again staggering seams and do other side.
http://i11.photobucket.com/albums/a1...elps/Joist.jpg

You're simply increasing the strength of the beams (joists). By adding 3-4 layers each side on both supporting joists your floor will be strong enough to support the load without deflection.

Just heard back from the contractor.

He said the way they would do it would be to throw in another joist and connect the other joists together with 8 foot 2x6s and then support the joists with one or two teleposts. The concrete floor will support 2000 lbs per square inch. As long as the telepost has a wide food print it should be ok.

AWESOME IDEA!! I like it!!

Ok, sorry but now I'm getting confused. In an earlier post you mentioned you had been told about not allowing basement framing to touch the ceiling (I assume that means joists). Something about floating floors and things settling etc. Your contractor now suggests adding joists & teleposts with wide footprints. The way I look at it, my wooden framing is a rather long, albeit narrow footprint and it is made of wood, therefore does have some room to flex no matter where it's attached. Also, as mentioned my basement already has framing supporting the joists down the center for support. How is that different than adding additional framing to support more weight. I'm certainly no expert on these matters and you have me wondering if what I'm planning is sound. Just trying to understand all the different angles here.

I guess I should elaborate.

The telepost is not bolted to the floor or the ceiling. Once a year you use a level to make sure the post and joist are still straight. If it moved you can adjust it via the nut at the top and loosen or tighten it accordingly to keep it straight. You can't do that with wood. :)

How large a tank can I get safely?
 

How large a tank can I get safely?

The house is from 1970.

The tank is to go perpendicular to 2"x8"joists which are 16" apart.
Parallel to the tank, (in the wall) is a beam composed of 4 2"x10"
Under one corner (of were the tanks is to be) there is a telescoping
support under the beam.

This seams strong, but ..
The 20 + 15 gallon tanks I have on a 4 legged metal 3/4" square tube stand ripple when a person or dog walks by.

Cheers,

Kamil