are youlooking for HOB or under sump how much room will you have top to bottom under sump? look at the Skimez on aquacave very good for sale foot print. I hve a buble magnus that Nac8 that does a really good job on my 120. on a 46 a Nac 4 would work
Ok so HOB kinda gets limited I would still look at the bubble magnus
Nac not sure what else is on that level. Maybe a cpr back pack 2. Or a Tunze if you have a big budget.