In a planted tank, circulation of nutrients, waste products and fresh water is an important factor in the overall health of your little eco-system. People often use powerheads to increase circulation, however, if you have a lot of dissolved organics, chemicals, and debris to filter out of your water column, then an extra filter, whether it's another power filter like the Mini or a larger cannister filter will provide both the movement and the clean-up. People have reported that inadequate circulation can be lethal to both plants and animal inhabitants from the build-up of excessive waste products and even nutrients within the confines of a tank. I think the last time I checked, the Mini (with the extra extension) is way cheaper than a powerhead or the cheapest cannister. Hope that helps.