ATP123
Huh?
If you put the tank up against the wall I would not worry about bracing / posting underneath. All your weight will bare on the foundation plate / exterior wall or how ever your house is built. I-joist, 2x10, and 2x12 are specced and design to handle a lot of load. I do not remember the exact amount. But if you just set your tank up against the wall you will not get the sponginess on your floor when walking by. Another thing is to look at the way your joist run and the beams in the crawl. Also you probably want to set it on a foundation wall and not a pony wall (small wall) it would probably be fine, but just in case.
If your going to the middle of the room tank scenario one thing to keep in mind is how big the room is and how far the joist span. If you go middle room I would defiantly add some support like Myteemouse had suggested. It is very easy to do. The only thing that would suck is the amount of room you have to work. One thing to keep in mind is even some small none weighted rooms have a sponginess to them. Then think about putting a 300 gal tank or whatever on it.
As for the cost of getting the material you could probably go to construction sites (if any around now days) and ask if they have a scrape pile. Could get the lumber for nothing sometimes.
Lastly, your house is built stronger then any crapy press board pre-fab. stand out there. Hope some of this helps.
True, but the wall that I was planning on puting it was not a support wall. It's just a wall to seperate the rooms and not the foundation one. Idon't have any space for the foundation side and whare there is space, there's windows.