Superleet
Fluidized beds performance are similar to trickle filters in their ability to assimilate Ammonia & Nitrite, with the final byproduct produced is nitrate. You need another device.....algae filters, Nitrate reactors, water changes, etc. to remove the built-up / excess Nitrate.
Since you are constructing a large coral garden a relatively low maintenance fitlration system would be your best approach, which is a Deep Sand Bed. The deeper the sandbed, the greater the area for faculative anaerobic bacteria to colonize and convertNitrateinto Nitrogen gas that can easily escape the tank - very basic description.
Good luck......