They work pretty good. I set up a 180 for a local pharmacist using one about 2 years ago. The tank is very healthy and everything is growing great! I did however stick a remora pro on there just tomake my self feel better. The skimmer pulls very little! Only thing i do not like is the amount of detritus that setles in the water intake chamber. But a good wet/dry vac can take care of that every 6 months or so! I will sat the macro does grow super fast in that mud!!