we were led
to believe that a biological filter was required to convert Amonia to
Nitrite then Nitrite to Nitrate,

Your live rock does that job for you.

The skimmer is for dissolved organics/phosphates which canister filters do not
do good at. Those two are food for algae so that's why people keep them low.

Live Rock
Skimmer
Sump w/Algae
is how I see it prioritized.
~John