In the senerio you are describing, if only a small amount of LR
were to be used, you would have to use some outher means of filtration... IMO
or EX, the bio wheel and other types of W/D media, will produce nitrates and with high levels and some med to low levels, corals will not survive. This is the reason it is talked so much in the forums about having 1.5 to 2 lbs per gal
of live rock...Then, there is no need for other means of filtration...Add a 4 to 6 inch DSB
and you will be set. I think you would have to do a lot of water changes to keep the nitrates and phosphates in check using other forms of filtration such as W/D Bio Wheels....