Hi I've had my 100 gallon tank now for about 5-6 months and love it, however I'm terrified that it'll fall through the floor taking out three water lines that lay underneath it. It's a 100 gallon acrylic tank 5'X18"X20" with a 15-20 gallon sump. I have 100LBS or so of live rock and 50 LBS of sand. The tank is located on a non load barring wall in the living room of the condo my fiancé and I rent. It's a single story condo with units on either end. The tank is parallel to the floor joyce spanning almost 2 2X10 joyces. I did buy some 4X4's and place them on the right side of the tank but couldn't get to left side of the tank due to heating duct. I am concerned about this because I can see and feel high and low spots on the floor, and lately hear a fair amount of cracking coming from the house as if the tank is falling through, or the house is just settling in from seasonal changes. The condo was built in 1996 and I'm fairly concerned about this I almost broke down the tank last night in fear of a structural failure. Any input would be greatly appreciated, thanks Matt.