Absolutely no need for them in any reef display
the system handles ammonia equally well with and without them
why would this matter becomes the next question, they’re certainly no harm to have extra surface area in a system
because knowing exactly how biofilters work allows us to manage threads like this
https://www.reef2reef.com/threads/official-sand-rinse-and-tank-transfer-thread.230281/page-54
where every job is removal of surface area. Notice the details that apply to your tank above: any reef on the internet can post there, we remove their entire sandbed
plus their bioballs if applicable plus any bricks in the sump, leaving only live rocks, and we transfer the same fish bioload using only those rocks into new tanks.
and for 54 pages, no bottle bac added. We strip reef tanks that whole thread using the rule applied to yours: live rocks in the display are enough for all reefs. This information is used to prevent reef tanks from crashing as we plan to move and swap and upgrade them
post a pic of your reef, let’s see how much surface area is in the display