I don't think it's the plants so much as their roots.....If you were to get java ferns and anubias and moss for instance, and tie them to driftwood, out of the substrate, you would be fine. Although, if you want my personal opinion.....I would just ditch the UGF and just have the Fluval 206.....As long as it's circulating the water, the filter in a nicely planted tank where the plants are growing steady, isn't really necessary beyond just mechanical water filtration and circulation. I think plants are a great filter just by themselves. I only use a filter as a water pump really, just to circulate water. I don't run carbon. Just the bio balls it came with, and a filter pad to catch any debris it might suck up. If you were to do this, you wouldn't need to worry about your UGF getting clogged anyway.