A couple of years ago our condo association made us get a structural engineer in to get our deck beefed up so we could hold the hot tub. The hot tub itself weighs very little (google softub) but holds 6 people and 300 gallons of water.

We had to double up every other joist, and install joist hangers to the ledger board. I think it was about a 10 foot span and we had to add two 2x12s to the beam (gluded with PL premium). The beam then had to be zig zagged with carriage bolts. We also had to add blocking in between each joist so that the joists would not twist.

I would say that you need to add another beam with 6x6s supporting it. I would have the 6x6s 4 feet down (or at least the pilings for the saddles down 4 feet).

Good luck