Hello and thank you for your message,
Unfortunately finding a hang on the back protein (HOB) skimmer for that larger of a tank will be more difficult as most are made for tanks under 75 gallons. One possiblity is using two HOB skimmers that are rated for smaller tank to accomodate your tanks size. I have linked a couple of skimmers below that might work for you:
AquaC Remora Pro-S (rated up to 120 gallons, probably would still need two)
Aqua Medic Turboflotor (rated up to 250 gallons, but realistically good for around 120-150 gallons)
Coralife Super Skimmer (rated up to 220 gallons)
Make sure to read the reviews about the skimmers left by our customers to get some good feedback on each of these. If you can add a sump to your system you will have a much better selection of skimmers available that will work much more efficiently.
If there is anything else we can do for you please let us know.
Marine Depot Customer Service