[danpik]

Water in that tank will weigh 425 Lbs. Not an excessive amount of weight. I would think that when all set up with decorations and such you might weigh in the neighborhood of 600 - 650 Lbs depending on what you put in there. I would not worry too much about the floor holding up to that weight. The tank won't crash through a hole in the floor unless you concentrate all of the weight onto one small area. Even then, the shear strength of wood is much higher than that. If the base that you set the tank onto spreads the weight out evenly the load placed onto each floor joust will be very small. For example, lets assume the tank is 48" wide and the stand it will be on is the same. If the floor structure is built with the joists on 16" centers there will be 4 joists carrying the load if the tank is set up perpendicular to the way they are running. Assuming a tank weight of 600 Lbs each joist will be supporting a load of 150 Lbs. If the tank is running parrallel to the joists then there would be at least two supporting the weight. Depending on the thickness of the flooring material the weight is also spread to the structure on either side of the load also. This is a real basic look at this situation and there are many variable to take into account in these situations. Was/is there any damage to the joists, are they properly sized and spaced are some of the obvious. How much other weight are they supporting is another. Probably the biggest is what is the structure like under the floor? for example has someone in the past removed a supporting wall? If the floor is level and feels solid then you should be OK. I had, in the past, an older house built around 1900 and had a 2500Lb waterbed on the second floor with no problems. In fact, if I remember correctly, there was a small (1/16") crack in the cieling below it and it barely opened up any more once the weight was added.

Dan