Sometimes I've answered the question in my mind, but it doesn't find its way into the response.
Run it all the time, unless there is an issue of it running out when you aren't there. In that case, like a small fountain at your office, you'd just shut it off at night and turn it back on in the morning.
Take a look at your 2010 Yearly chart - a bubbling fountain isn't the only option to activate that yearly Abundance start in the West.
As for a fish tank...is there just a couple small fish in it for it's size, or are there a good representation of fish in it? A single, non-moving, or small fish would classify the water as "Moving water," unless the tank itself was small. Now look at your 20-year period and yearly stars. Which sector calls for the type of "water" your fish tank represents? Just don't place it in a bedroom.