So, I'm moving at the end of the month. It will be on the third floor of an older, but well maintained apt building. I am looking to do some tank upgrades. With all that said, and without any more details, whats the general opinion on what a floor like that could hold? Without a secured, concrete floor under it? I want as big a tank as possible without concern. Clearly, plenty of household appliances aren't light either......opinions?