An aquarium is the most obvious - and probably most popular - water feature in the home, with aesthetic as well as auspicious qualities. In terms of fung shui, the significant volume of water within an aquarium will activate any positive chi. The water should be topped up as it evaporates and it should always be kept clean; dirty or stagnant water is a source of sha chi, or negative energy. For beneficial energy to collect, the water should be visible and exposed, so if your aquarium has a lid, try to remove it for short periods. Water towers containing plastic fish or colourful lights are also acceptable fung shui features. They can be moved easily around the house to activate whichever beneficial energy happens to be in situ. They also fit in with modern decor and so don't stand out as obvious fung shui symbols. Small water features will only have an effect in smaller living or working spaces, though. Water-filled vases stimu- late romance energy rather than wealth chi because the water does not circulate. The surface area of the water is also a factor. Some fung shui masters consider table or desktop fountains to be too small to have much effect, because the volume of water is insignificant. You need at least 11/2 litres of water for fung shui efficacy.