Do you mean a regular hob
or canister filter with carbon, floss, maybe biowheel?
If so, they are alright on some tanks. Maybe on a fo
tank. I have one on each of my tanks but have removed the floss and filled them with lr
rubble instead. If you have plenty of lr
and a good skimmer you don't need a hob
except maybe for the occasional carbon use. If you have a sump you can put the carbon in it and not even have a hob
. I only keep the hob
because my heater is part of it(tetratec 500 w/200w heater.) otherwise I wouldn't even have it. I also have a hob
aquaclear300 that's been converted to a refugium. If you already have it, it can come in handy but if you are planning on going with a reef setup, save the money for a good skimmer and live rock.