The problem with UGFs are they are TOO efficient. They typically move to much water to get any anerobic nitra
te reduction, and will out-compete LR
when it comes to ammonia/nitrite reduction.
The main advantage of LR
and DSBs is they can perform other decomposition other than ammonia/nitrite, while UFG's can't. Heck , a 5" biowheel on a Emperor 280 can do just as much ammonia/nitrite reduction as a 55gallon tank with UFG, so that part is a solution in search of a problem. One advantage of UFG's is they tend to act as a mechanical filter and hence keep your water pretty clear though. The bad is you can't change the filer unless you like gravel sucking.
For me, the verdict is still out on DSB
's, but lots of LR
and some strong water flow is a 'no-brainer' in my book. I'm currently experimenting with a DSB
with a slow flow plumbing system embedded deeply, the rig installed in a tank that's pushing high nitrate levels. My theory being that DSB
's need a little help to do what they are designed to