ghbrewer;970903 wrote: Just for future reference, and for others that might be considering the same. I would like to provide a little basis for my statements. Anytime you are placing a large tank on any floor, other than a concrete slab (although when you get above 300 gallons, i suggest looking at the slabs as well), you have to consider the strength of the floor beneath the tank. In the case of the OP, he is considering setting up a 210 gallon tank on a floor that is wood frame supported by cinder block piers.
In this case, the tank itself will weigh somewhere between 400 and 500 lbs empty. Then you add in the water that will weigh between 1700 to 1800 lbs, so you are now looking at around 2100 to 2300 lbs. Add in the weight of however much rock you are going to use (will displace some water, but for the sake of conservatism and a little safety factor we will ignore this) and the stand, sump (consider this too), equipment, etc...; you could easily be looking at well over 3000 lbs sitting in a footprint of approximately (6-ft x 2-ft, or 12 square feet).
Most residential homes, at least in the last 20 to 30 years, have been built in accordance with international building codes (I say most, but I have seen a lot of old/poorly built homes that I cannot imagine would come anywhere near meeting today's standards). Generally speaking, in today's construction, living area floors are built to withstand a live load of 40 pounds per square foot (psf). There is a lot of misinformation on the web regarding live and dead loads. So for the sake of simplicity, a live load is anything that can be moved around (i.e. furniture, people, planters, and...aquariums). Dead loads are the loads produced by the structure itself (i.e. the weight of the framing itself, drywall, windows, roofing, etc...). So again, living areas are generally designed to support 40 psf of live load. Sleeping areas, or bedrooms and such, are usually only designed to support 20 psf of live load.
So "simply speaking" your tank and its peripherals are going to be producing around 250 psf of live load, based on 3000 lbs over 12 sq. ft. So, as you can see, a 210 gallon tank is going to be placing over 6x the amount of live load that most residential living area floors (stick frame construction, or those with wooden floor joists) are designed to withstand, and around 12x the load for a bedroom area.
Again, this is a very simplistic approach to looking at this, and in reality there is a lot of other things to consider, such as stand construction, joist type, size and spacing, bearing plates, structure and proximity of neighboring walls, etc... So that is why I suggest that a professional engineer (and I suggest getting one with a PE license, and whom specializes in structural engineering) take a look at what you are planning to do, as well as come to your house to take a look. They are more than capable to offer advice on how to get the job done properly.
