The 650's refugium is 13 gallons with the divider set at the wider setting and when you include the area freed up by removal of the filter socks and their holders. This can be increased to 17+gallons by subdividing the skimmer chamber using rigid coarse filtration pad or a more complex divider.
I'm growing red algae in the former filter sock area (10" x 9") and green algae, predominantly chaeto in the 9" x 23" refugium area beyond where the filter socks would normally reside. Depth is 10.5", light is a Zedlight S200 refugium light centrered over the 9" x 23" zone. This provides strong illumination for the chaeto and bright but less strong light for the reds which are clearly loving that. Skimmer is a Icecap K2-200. Return pump is a Reef Octopus Varios 8.
The Triton system took a while to re-stabilize the formerly KZ-system tank tank but has now established stable, low nutrient conditions in our Peninsula 650. Only issues we suffered came from my impatience producing an outbreak of one of the red algae in the display tank. Like all self inflicted problems that one has taken longer to fix than cause but once the algae in the refugium reached a critical mass growth in the display tank dropped precipitously and weeding it out by hand has done the rest.
One recommendation, add the Triton reagents next to the drain, upstream of the refugium rather than in the return pump chamber. Former results in your refugium seeing the nutrients first which I think minimizes feeding of any algae you may have in the display tank.
As for the 650 itself its a fabulous setup. Great look, lots of real estate and appropriately sized, quality components.