? I like Big Sumps ?
I run one brackish 55g community with a 42g sump and it's working well.
You can have a 55 with HOBs or cannisters: that nets you 50- 52g of water bare.
I get 80 gals easily with a big sump.
The extra water is a much bigger deal than having extra filtration.
More water + cheapo filter > less water + $$$ FX6
I just saw my 5th generation of fry in this system. 
I run one brackish 55g community with a 42g sump and it's working well.
You can have a 55 with HOBs or cannisters: that nets you 50- 52g of water bare.
I get 80 gals easily with a big sump.
The extra water is a much bigger deal than having extra filtration.
More water + cheapo filter > less water + $$$ FX6