there good units but the bioballs trap waste over time breaking down and causing high nitrates. Most have LR
in the tank and take out the bio balls over time.
inline??? not sure what you mean here.... Is it hooked to your return pump? If so you should look into putting it on its own pump. A UV
is not 100 effective unless you run water through it at a slow rate.
is used to kill bacteria, parasites, free floating algae... If there are particles of sand, crap it will do nothing to them just passes through the light.