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Why shouldn't there be water behind the sofa

There should be no water behind the sofa, so placing the fish tank behind the sofa is a feng shui taboo. For the same reason, it is not appropriate to place fish tanks, feng shui wheels and other decorative items with water on the low cabinet behind the sofa. Of course, for a sofa with no backing at the back, it would be beneficial and harmless to fill the space behind with evergreen plants.