how much water can you be losing... ive also got a 55g sump.. i backflow around 10 gallons (4"s) of water when power goes out...
worst case scinario (vent hole on the spraybar plugs + overflow empties) i drain around another 15 gallons from the tank to the sump..
either way though.. im not talking water levels... youve got 8? gallons of media in a 55 gallon sump...
im just not understanding why you wouldnt have media filling every space that water goes both above and below the water line
55g sump on the 220g tank
the front of the stand is leaning against the couch
add 4" of water when the power goes out + another 5" if everything goes wrong which leaves me another 3" or so to have the sump extra full durring the summer so i dont have to do constant topoffs.. the white bowl (bottom middle) is full of all the "magic super rocks" (ceramic rings/eheim subpro/stuff that looks like cocopuffs) that have come with various hob and canister filters..
Your setup looks like a bit of overkill to me, but then again, mine looks empty to you. I suppose it depends how much bio media you think you need. I run 3 other filters besides my sump, so my wet/dry is not doing all the work. My water params are near perfect, so no need for more bio in my sump. I also use that open sump space for my heaters and my fry. Having the open space also helps when I clean the gunk off the bottom.