another thing about UGF
is a problem with longevity ... they build up a "stockpile" of 'nuclear' waste underneath the filter grid ... eventually, after many many months of this stockpiling, any distruption of the grid will send a cloud of highly toxic waste into your water.
Only ways I've found to combat this is
don't distrupt the grid
vacuum under the grid by running a siphon tube down each lift tube
run the filter with reverse flow, so water is forced under the grid and up through the gravel, this will keep the waste suspended in the water column, for your pengiun to filter out.