On exterior walls the floor joints r supported by ur concrete foundation I think u r doing a 220 gallon tank water weighs 8.34 lbs per gallon so that's 1835 lbs the average refrigerator weighs about 300 lbs. So if u feel safe setting six refrigerators against the wall in ur living room then u should b ok
. Not sure of age of house if u have floor trusses instead of joists they will usually support a significantly higher load. But the tank should be run across the joists not with the joists in either case.
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