I'm going to sound like a broken record , but UGF
's aren't as bad as people make them out to be . They are great filters in certain situations . They are fine for tanks 30 gallons or smaller , for small fish such as tetras & rasboras , they are great for raising fry , & for tanks with fake plants or plants tied to driftwood or rocks .
They are not good for large messy fish such as plecos , cichlids , clown loaches , bala sharks , goldfish , ect . Cichlids in particular should not be used with UGF
's , since they love to dig up the gravel thereby exposing the plates & making the filter almost useless . Live plants in the substrate will not thrive as well in tanks with UGF
To say that UGF
's clog easily , are high maintenance , & are fish killers is an urban mythe on par with alligators living in the sewers of New York . All you have to do is weekly vacuming of the substrate , just like in any other tank , & a churning of the gravel with a gravel cleaner once a month . Any competant aquarist should be doing these things regardless of the type of filter that they are using . As for the gunk under the plates , it is not toxic . By the time it reaches the bottom , the bacteria living in the gravel have broken it down into harmless organic material . I have had this gunk come up with fry in the tank with no ill effects . To get rid of it , push the gravel away from your uptake tubes , remove the tubes , & then stick a small diametre hose into the opening & under the plates to siphon the gunk out . You do not have to empty your tank completely & remove the plates to clean the gunk out . That's simply a ridiculous & uninformed claim .
's provide outstanding biological filtration , but no mechanical filtration . If you do plan to use a UGF
,you can use it in conjuntion with a HOB
filter . All in all I would recommend a cannister or HOB
filter , but I wouldn't dismiss UGF
's entirely .