Hi BAR, Wife and I are examining the possibility of putting up a 100g display with max 50g(of water volume) sump. We do have one serious concern. Our house is not on a concrete slab, but has a wood joist floor. I've looked through the internet and have seen mixed information so i thought i'd go to the place with some local real-world experience. Original house was bult in late 1940's, the tank location would be the kitchen which was remodeled and expanded within the last 10 years. We've had a tank with total water volume of 60 gallons in the old part of the house, and a 30g cube in the kitchen with no problems. I realize that this is all much less than what we are looking to get, but it's a starting point. Any and all input would be great, especially contact information for anyone who could crawl under our house and give a professional opinion.