<https://forum.aquariumcoop.com/topic/12409-why-are-ugfs-not-very-popular/#comment-97158>
<http://schema.org/text>
"I had an UGF years ago and while it did a good job of keeping the water clean, I always had this feeling of, \"what's under there?\" I like to be able to clean a filter and know more of what's going on. After that one I never tried it again.\n "
<https://forum.aquariumcoop.com/topic/12409-why-are-ugfs-not-very-popular/>