Most people are put off MTS by finding a horde of them at night time when the lights are off, and they happened to have looked at the tank with the room light on. Personally I'm not bothered about how the tank looks when the lights are off so long as everything is healthy (fish thriving, plants growing, not too much algae and ammonia, nitrite and nitrate levels in check). If you believe that the MTS are pushing your stocking density over the edge, or you just don't like the look of them, then you'll likely want to take action and get rid.